Inorganic oxide articles with thin, durable anti reflective structures

ABSTRACT

An article that includes: an inorganic oxide substrate having opposing major surfaces; and an optical film structure disposed on a first major surface of the substrate, the optical film structure comprising one or more of a silicon-containing oxide, a silicon-containing nitride and a silicon-containing oxynitride and a physical thickness from about 50 nm to less than 500 nm. The article exhibits a hardness of 8 GPa or greater measured at an indentation depth of about 100 nm or a maximum hardness of 9 GPa or greater measured over an indentation depth range from about 100 nm to about 500 nm, the hardness and the maximum hardness measured by a Berkovich Indenter Hardness Test. Further, the article exhibits a single-side photopic average reflectance that is less than 1%.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation application of U.S. application Ser.No. 16/541,835, filed Aug. 15, 2019, still pending, which claims thebenefit of priority under 35 U.S.C. § 119(e) of U.S. ProvisionalApplication No. 62/765,081, filed on Aug. 17, 2018, the contents ofwhich are relied upon and incorporated herein by reference in itsentirety.

BACKGROUND

The disclosure relates to inorganic oxide articles with thin, durableanti-reflective structures and methods for making the same, and moreparticularly to articles with thin, multi-layer anti-reflectivecoatings.

Cover articles are often used to protect devices within electronicproducts, to provide a user interface for input and/or display, and/orfor many other functions. Such products include mobile devices, forexample smart phones, smart watches, mp3 players and computer tablets.Cover articles also include architectural articles, transportationarticles (e.g., interior and exterior display and non-display articlesused in automotive applications, trains, aircraft, sea craft, etc.),appliance articles, or any article that may benefit from sometransparency, scratch-resistance, abrasion resistance or a combinationthereof. These applications often demand scratch-resistance and strongoptical performance characteristics, in terms of maximum lighttransmittance and minimum reflectance. Furthermore, for some coverapplications it is beneficial that the color exhibited or perceived, inreflection and/or transmission, does not change appreciably as theviewing angle is changed. In display applications, this is because, ifthe color in reflection or transmission changes with viewing angle to anappreciable degree, the user of the product will perceive a change incolor or brightness of the display, which can diminish the perceivedquality of the display. In other applications, changes in color maynegatively impact the aesthetic appearance or other functional aspectsof the device.

These display and non-display articles are often used in applications(e.g., mobile devices) with packaging constraints. In particular, manyof these applications can significantly benefit from reductions inoverall thickness, even reductions of a few percent. In addition, manyof the applications that employ such display and non-display articlesbenefit from low manufacturing cost, e.g., through the minimization ofraw material costs, minimization of process complexity and yieldimprovements. Smaller packaging with optical and mechanical propertyperformance attributes comparable to existing display and non-displayarticles can also serve the desire for reduced manufacturing cost (e.g.,through less raw material costs, through reductions in the number oflayers in an anti-reflective structure, etc.).

The optical performance of cover articles can be improved by usingvarious anti-reflective coatings; however, known anti-reflectivecoatings are susceptible to wear or abrasion. Such abrasion cancompromise any optical performance improvements achieved by theanti-reflective coating. For example, optical filters are often madefrom multilayer coatings having differing refractive indices and madefrom optically transparent dielectric material (e.g., oxides, nitrides,and fluorides). Most of the typical oxides used for such optical filtersare wide band-gap materials, which do not have the requisite mechanicalproperties, for example hardness, for use in mobile devices,architectural articles, transportation articles or appliance articles.Most nitrides and diamond-like coatings may exhibit high hardnessvalues, which can be correlated to improved abrasion resistance, butsuch materials do not exhibit the desired transmittance for suchapplications.

Abrasion damage can include reciprocating sliding contact from counterface objects (e.g., fingers). In addition, abrasion damage can generateheat, which can degrade chemical bonds in the film materials and causeflaking and other types of damage to the cover glass. Since abrasiondamage is often experienced over a longer term than the single eventsthat cause scratches, the coating materials disposed experiencingabrasion damage can also oxidize, which further degrades the durabilityof the coating.

Accordingly, there is a need for new cover articles, and methods fortheir manufacture, which are abrasion resistant, have acceptable orimproved optical performance and thinner optical structures.

SUMMARY

According to some embodiments of the disclosure, an article is providedthat includes: an inorganic oxide substrate having opposing majorsurfaces; and an optical film structure disposed on a first majorsurface of the inorganic oxide substrate, the optical film structurecomprising one or more of a silicon-containing oxide, asilicon-containing nitride and a silicon-containing oxynitride and aphysical thickness from about 50 nm to less than 500 nm. The articleexhibits a hardness of 8 GPa or greater measured at an indentation depthof about 100 nm or a maximum hardness of 9 GPa or greater measured overan indentation depth range from about 100 nm to about 500 nm, thehardness and the maximum hardness measured by a Berkovich IndenterHardness Test. Further, the article exhibits a single-side photopicaverage reflectance that is less than 1%.

According to some embodiments of the disclosure, an article is providedthat includes: an inorganic oxide substrate having opposing majorsurfaces; and an optical film structure disposed on a first majorsurface of the inorganic oxide substrate, the optical film structurecomprising a physical thickness from about 50 nm to less than 500 nm anda plurality of alternating high index and low index layers with a firstlow index layer on the first major surface and a capping low indexlayer. Each layer comprises one or more of a silicon-containing oxide, asilicon-containing nitride and a silicon-containing oxynitride. Therefractive index of the low index layers is within a range of arefractive index of the inorganic oxide substrate such that therefractive index of the low index layers is less than about 1.8, and thehigh index layer comprises a refractive index that is greater than 1.8.The high index layer exhibits a maximum hardness of 18 GPa or greater asmeasured by a Berkovich Indenter Hardness Test over an indentation depthfrom about 100 nm to about 500 nm on a hardness test stack comprisingthe high index layer with a physical thickness of about 2 micrometers(microns or μm) disposed on the inorganic oxide substrate. Further, thearticle exhibits a single-side photopic average reflectance that is lessthan 1%.

According to some embodiments of the disclosure, an article is providedthat includes: an inorganic oxide substrate having opposing majorsurfaces; and an optical film structure disposed on a first majorsurface of the inorganic oxide substrate, the optical film structurecomprising a physical thickness from about 50 nm to less than 500 nm anda plurality of alternating high index and low index layers with a firstlow index layer on the first major surface and a capping low indexlayer. Each layer comprises one or more of a silicon-containing oxide, asilicon-containing nitride and a silicon-containing oxynitride. Therefractive index of the low index layers is within a range of arefractive index of the inorganic oxide substrate such that therefractive index of the low index layers is less than about 1.8, and thehigh index layer comprises a refractive index that is greater than 1.8.The optical film structure further comprises 30% or more of the highindex layer by volume. Further, the article exhibits a single-sidephotopic average reflectance that is less than 1%.

According to some embodiments of the disclosure, an article is providedthat includes: an inorganic oxide substrate having opposing majorsurfaces; and an optical film structure disposed on a first majorsurface of the inorganic oxide substrate, the optical film structurecomprising a plurality of alternating high index and low index layerswith a first low index layer on the first major surface of the substrateand a capping low index layer. The refractive index of the low indexlayers is within a range of a refractive index of the inorganic oxidesubstrate such that the refractive index of the low index layers is lessthan about 1.8, and the high index layer has a refractive index that isgreater than 1.8. The article exhibits a hardness of 8 GPa or greatermeasured at an indentation depth of about 100 nm or a maximum hardnessof 9 GPa or greater measured over an indentation depth range from about100 nm to about 500 nm, the hardness and the maximum hardness measuredby a Berkovich Indenter Hardness Test. The optical film structurefurther comprises 35% or more of the high index layer by volume. Thearticle exhibits a single-side photopic average reflectance that is lessthan 1%. The high index layer exhibits a maximum hardness of 18 GPa orgreater as measured by a Berkovich Indenter Hardness Test over anindentation depth from about 100 nm to about 500 nm on a hardness teststack comprising the high index layer with a physical thickness of about2 microns disposed on the inorganic oxide substrate. Further, thearticle exhibits an a* value, in reflectance, from about −10 to +2 and ab* value, in reflectance, from −10 to +2, the a* and b* values eachmeasured on the optical film structure at a normal incident illuminationangle.

Additional features and advantages will be set forth in the detaileddescription which follows, and in part will be readily apparent to thoseskilled in the art from that description or recognized by practicing theembodiments as described herein, including the detailed descriptionwhich follows, the claims, as well as the appended drawings.

It is to be understood that both the foregoing general description andthe following detailed description are merely exemplary, and areintended to provide an overview or framework to understanding the natureand character of the claims.

The accompanying drawings are included to provide a furtherunderstanding, and are incorporated in and constitute a part of thisspecification. The drawings illustrate one or more embodiment(s) and,together with the description, serve to explain, by way of example,principles and operation of the disclosure. It is to be understood thatvarious features of the disclosure disclosed in this specification andin the drawings can be used in any and all combinations. By way ofnon-limiting examples, the various features of the disclosure may becombined with one another according to the following embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features, aspects and advantages of the presentdisclosure are better understood when the following detailed descriptionof the disclosure is read with reference to the accompanying drawings,in which:

FIG. 1 is a side view of an article, according to one or moreembodiments;

FIG. 2A is a side view of an article, according to one or moreembodiments;

FIG. 2B is a side view of an article, according to one or moreembodiments;

FIG. 3 is a side view of an article, according to one or moreembodiments;

FIG. 4A is a plan view of an exemplary electronic device incorporatingany of the articles disclosed herein;

FIG. 4B is a perspective view of the exemplary electronic device of FIG.4A;

FIG. 5 is a perspective view of a vehicle interior with vehicularinterior systems that may incorporate any of the articles disclosedherein;

FIG. 6 is a plot of hardness vs. indentation depth for articlesdisclosed herein;

FIG. 7 is a plot of first-surface, reflected color coordinates measuredat, or calculated for, near-normal incidence of articles disclosedherein;

FIG. 8 is a plot of specular component excluded (SCE) values obtainedfrom articles of the disclosure as subjected to the Alumina SCE Test andobtained from a comparative anti-reflective coating comprising niobiaand silica;

FIG. 9 is a plot of hardness vs. indentation depth for a hardness teststack of high refractive index layer material, according to anembodiment, that is suitable for use in the anti-reflective coatings andarticles of the disclosure; and

FIG. 10 is a plot of transmittance (one-sided) vs. wavelength ofarticles according to the disclosure that comprise five- and seven-layeranti-reflective coatings.

DETAILED DESCRIPTION

In the following detailed description, for purposes of explanation andnot limitation, example embodiments disclosing specific details are setforth to provide a thorough understanding of various principles of thepresent disclosure. However, it will be apparent to one having ordinaryskill in the art, having had the benefit of the present disclosure, thatthe present disclosure may be practiced in other embodiments that departfrom the specific details disclosed herein. Moreover, descriptions ofwell-known devices, methods and materials may be omitted so as not toobscure the description of various principles of the present disclosure.Finally, wherever applicable, like reference numerals refer to likeelements.

Ranges can be expressed herein as from “about” one particular value,and/or to “about” another particular value. As used herein, the term“about” means that amounts, sizes, formulations, parameters, and otherquantities and characteristics are not and need not be exact, but may beapproximate and/or larger or smaller, as desired, reflecting tolerances,conversion factors, rounding off, measurement error and the like, andother factors known to those of skill in the art. When the term “about”is used in describing a value or an end-point of a range, the disclosureshould be understood to include the specific value or end-point referredto. Whether or not a numerical value or end-point of a range in thespecification recites “about,” the numerical value or end-point of arange is intended to include two embodiments: one modified by “about,”and one not modified by “about.” It will be further understood that theendpoints of each of the ranges are significant both in relation to theother endpoint, and independently of the other endpoint.

The terms “substantial,” “substantially,” and variations thereof as usedherein are intended to note that a described feature is equal orapproximately equal to a value or description. For example, a“substantially planar” surface is intended to denote a surface that isplanar or approximately planar. Moreover, “substantially” is intended todenote that two values are equal or approximately equal. In someembodiments, “substantially” may denote values within about 10% of eachother, for example within about 5% of each other, or within about 2% ofeach other.

Directional terms as used herein—for example up, down, right, left,front, back, top, bottom—are made only with reference to the figures asdrawn and are not intended to imply absolute orientation.

Unless otherwise expressly stated, it is in no way intended that anymethod set forth herein be construed as requiring that its steps beperformed in a specific order. Accordingly, where a method claim doesnot actually recite an order to be followed by its steps, or it is nototherwise specifically stated in the claims or descriptions that thesteps are to be limited to a specific order, it is in no way intendedthat an order be inferred, in any respect. This holds for any possiblenon-express basis for interpretation, including: matters of logic withrespect to arrangement of steps or operational flow; plain meaningderived from grammatical organization or punctuation; the number or typeof embodiments described in the specification.

As used herein, the singular forms “a,” “an” and “the” include pluralreferents unless the context clearly dictates otherwise. Thus, forexample, reference to a “component” includes embodiments having two ormore such components, unless the context clearly indicates otherwise.

Embodiments of the disclosure relate to inorganic oxide articles withthin, durable anti-reflective structures and methods for making thesame, and more particularly to articles with thin, multi-layeranti-reflective coatings exhibiting abrasion resistance, lowreflectivity, and colorless transmittance and/or reflectance.Embodiments of these articles possess anti-reflective optical structureswith a total physical thickness of less than 500 nm, while maintainingthe hardness, abrasion resistance and optical properties associated withthe intended applications for these articles (e.g., as covers, housingsand substrates for display devices, interior and exterior automotivecomponents, etc.).

Referring to FIG. 1, the article 100 according to one or moreembodiments may include a substrate 110, and an anti-reflective coating120 (also referred herein as an “optical film structure”) disposed onthe substrate. The substrate 110 includes opposing major surfaces 112,114 and opposing minor surfaces 116, 118. The anti-reflective coating120 is shown in FIG. 1 as being disposed on a first opposing majorsurface 112; however, the anti-reflective coating 120 may be disposed onthe second opposing major surface 114 and/or one or both of the opposingminor surfaces, in addition to or instead of being disposed on the firstopposing major surface 112. The anti-reflective coating 120 forms ananti-reflective surface 122.

The anti-reflective coating 120 includes at least one layer of at leastone material. The term “layer” may include a single layer or may includeone or more sub-layers. Such sub-layers may be in direct contact withone another. The sub-layers may be formed from the same material or twoor more different materials. In one or more alternative embodiments,such sub-layers may have intervening layers of different materialsdisposed therebetween. In one or more embodiments a layer may includeone or more contiguous and uninterrupted layers and/or one or morediscontinuous and interrupted layers (i.e., a layer having differentmaterials formed adjacent to one another). A layer or sub-layers may beformed by a discrete deposition or a continuous deposition process. Inone or more embodiments, the layer may be formed using only continuousdeposition processes, or, alternatively, only discrete depositionprocesses.

As used herein, the term “dispose” includes coating, depositing and/orforming a material onto a surface. The disposed material may constitutea layer, as defined herein. The phrase “disposed on” includes theinstance of forming a material onto a surface such that the material isin direct contact with the surface and also includes the instance wherethe material is formed on a surface, with one or more interveningmaterial(s) between the disposed material and the surface. Theintervening material(s) may constitute a layer, as defined herein.

According to one or more embodiments, the anti-reflective coating 120 ofthe article 100 (e.g., as shown and described in connection with FIG. 1)can be characterized with abrasion resistance according to the AluminaSCE Test. As used herein, the “Alumina SCE Test” is conducted bysubjecting a sample to a commercial 800 grit alumina sandpaper (10 mm×10mm) with a total weight of 0.7 kg for fifty (50) abrasion cycles, usingan ˜1″ stroke length powered by a Taber Industries 5750 linear abrader.Abrasion resistance is then characterized, according to the Alumina SCETest, by measuring reflected specular component excluded (SCE) valuesfrom the abraded samples according to principles understood by thosewith ordinary skill in the field of the disclosure. More particularly,SCE is a measure of diffuse reflection off of the surface of theanti-reflection coating 120, as measured using a Konica-Minolta CM700Dwith a 6 mm diameter aperture. According to some implementations, theanti-reflective coating 120 of the articles 100 can exhibit SCE values,as obtained from the Alumina SCE Test, of less than 0.4%, less than0.2%, less than 0.18%, less than 0.16%, or even less than 0.08%. Incontrast, commercial anti-reflection coatings (such as a six-layerNb₂O₅/SiO₂ multilayer coating) have a post-sandpaper abrasion SCE valueof greater than 0.6%. Abrasion-induced damage increases the surfaceroughness leading to the increase in diffuse reflection (i.e., SCEvalues). Lower SCE values indicates less severe damage, indicative ofimproved abrasion resistance.

The anti-reflective coating 120 and the article 100 may be described interms of a hardness measured by a Berkovich Indenter Hardness Test.Further, those with ordinary skill in the art can recognize thatabrasion resistance of the anti-reflective coating 120 and the article100 can be correlated to the hardness of these elements. As used herein,the “Berkovich Indenter Hardness Test” includes measuring the hardnessof a material on a surface thereof by indenting the surface with adiamond Berkovich indenter. The Berkovich Indenter Hardness Testincludes indenting the anti-reflective surface 122 of the article 100 orthe surface of the anti-reflective coating 120 (or the surface of anyone or more of the layers in the anti-reflective coating) with thediamond Berkovich indenter to form an indent to an indentation depth inthe range from about 50 nm to about 1000 nm (or the entire thickness ofthe anti-reflective coating or layer, whichever is less) and measuringthe hardness from this indentation at various points along the entireindentation depth range, along a specified segment of this indentationdepth (e.g., in the depth range from about 100 nm to about 500 nm), orat a particular indentation depth (e.g., at a depth of 100 nm, at adepth of 500 nm, etc.) generally using the methods set forth in Oliver,W. C. and Pharr, G. M., “An improved technique for determining hardnessand elastic modulus using load and displacement sensing indentationexperiments”, J. Mater. Res., Vol. 7, No. 6, 1992, 1564-1583; andOliver, W. C. and Pharr, G. M., “Measurement of Hardness and ElasticModulus by Instrument Indentation: Advances in Understanding andRefinements to Methodology”, J. Mater. Res., Vol. 19, No. 1, 2004, 3-20.Further, when hardness is measured over an indentation depth range(e.g., in the depth range from about 100 nm to about 500 nm), theresults can be reported as a maximum hardness within the specifiedrange, wherein the maximum is selected from the measurements taken ateach depth within that range. As used herein, “hardness” and “maximumhardness” both refer to as-measured hardness values, not averages ofhardness values. Similarly, when hardness is measured at an indentationdepth, the value of the hardness obtained from the Berkovich IndenterHardness Test is given for that particular indentation depth.

Typically, in nanoindentation measurement methods (such as by using aBerkovich indenter) of a coating that is harder than the underlyingsubstrate, the measured hardness may appear to increase initially due todevelopment of the plastic zone at shallow indentation depths and thenincreases and reaches a maximum value or plateau at deeper indentationdepths. Thereafter, hardness begins to decrease at even deeperindentation depths due to the effect of the underlying substrate. Wherea substrate having an increased hardness compared to the coating isutilized, the same effect can be seen; however, the hardness increasesat deeper indentation depths due to the effect of the underlyingsubstrate.

The indentation depth range and the hardness values at certainindentation depth range(s) can be selected to identify a particularhardness response of the optical film structures and layers thereof,described herein, without the effect of the underlying substrate. Whenmeasuring hardness of the optical film structure (when disposed on asubstrate) with a Berkovich indenter, the region of permanentdeformation (plastic zone) of a material is associated with the hardnessof the material. During indentation, an elastic stress field extendswell beyond this region of permanent deformation. As indentation depthincreases, the apparent hardness and modulus are influenced by stressfield interactions with the underlying substrate. The substrateinfluence on hardness occurs at deeper indentation depths (i.e.,typically at depths greater than about 10% of the optical film structureor layer thickness). Moreover, a further complication is that thehardness response utilizes a certain minimum load to develop fullplasticity during the indentation process. Prior to that certain minimumload, the hardness shows a generally increasing trend.

At small indentation depths (which also may be characterized as smallloads) (e.g., up to about 50 nm), the apparent hardness of a materialappears to increase dramatically versus indentation depth. This smallindentation depth regime does not represent a true metric of hardness;but instead, it reflects the development of the aforementioned plasticzone, which is related to the finite radius of curvature of theindenter. At intermediate indentation depths, the apparent hardnessapproaches maximum levels. At deeper indentation depths, the influenceof the substrate becomes more pronounced as the indentation depthsincrease. Hardness may begin to drop dramatically once the indentationdepth exceeds about 30% of the optical film structure thickness or thelayer thickness.

As noted above, those with ordinary skill in the art can considervarious test-related considerations in ensuring that the hardness andmaximum hardness values of the coating 120 and article 100 obtained fromthe Berkovich Indenter Hardness Test are indicative of these elements,rather than being unduly influenced by the substrate 110, for example.Further, those with ordinary skill in the art can also recognize thatthe embodiments of the disclosure surprisingly demonstrate high hardnessvalues associated with the anti-reflective coating 120 despite therelatively low thickness of the coating 120 (i.e., <500 nm). Indeed, asevidenced by the Examples detailed below in subsequent sections, thehardness of the high refractive index (RI) layer(s) 130B within ananti-reflective coating (see, e.g., FIGS. 2A and 2B), can significantlyinfluence the overall hardness and maximum hardness of theanti-reflective coating 120 and article 100, despite the relatively lowthickness values associated with these layers. This is surprisingbecause of the above test-related considerations, which detail howmeasured hardness is directly influenced by the thickness of a coating,for example the anti-reflective coating 120. In general, as a coating(over a thicker substrate) is reduced in thickness, and as the volume ofharder material (e.g., as compared to other layers within the coatinghaving a lower hardness) in the coating decreases, it would be expectedthat the measured hardness of the coating will trend toward the hardnessof the underlying substrate. Nevertheless, the articles 100 of thedisclosure, as including the anti-reflective coating 120 (and as alsoexemplified by the Examples outlined in detail below), surprisinglyexhibit significantly high hardness values in comparison to theunderlying substrate, thus demonstrating a unique combination of coatingthickness (<500 nm), volumetric fraction of higher hardness material andoptical properties.

In some embodiments, the anti-reflective coating 120 of the article 100may exhibit a hardness of greater than about 8 GPa, as measured on theanti-reflective surface 122, by a Berkovich Indenter Hardness Test at anindentation depth of about 100 nm. The antireflective coating 120 mayexhibit a hardness of about 8 GPa or greater, about 9 GPa or greater,about 10 GPa or greater, about 11 GPa or greater, about 12 GPa orgreater, about 13 GPa or greater, about 14 GPa or greater, or about 15GPa or greater by a Berkovich Indenter Hardness Test at an indentationdepth of about 100 nm. The article 100, including the anti-reflectivecoating 120 and any additional coatings, as described herein, mayexhibit a hardness of about 8 GPa or greater, about 10 GPa or greater orabout 12 GPa or greater, as measured on the anti-reflective surface 122by a Berkovich Indenter Hardness Test at an indentation depth of about100 nm. Such measured hardness values may be exhibited by theanti-reflective coating 120 and/or the article 100 over an indentationdepth of about 50 nm or greater or about 100 nm or greater (e.g., fromabout 100 nm to about 300 nm, from about 100 nm to about 400 nm, fromabout 100 nm to about 500 nm, from about 100 nm to about 600 nm, fromabout 200 nm to about 300 nm, from about 200 nm to about 400 nm, fromabout 200 nm to about 500 nm, or from about 200 nm to about 600 nm).Similarly, maximum hardness values of about 8 GPa or greater, about 9GPa or greater, about 10 GPa or greater, about 11 GPa or greater, about12 GPa or greater, about 13 GPa or greater, about 14 GPa or greater, orabout 15 GPa or greater by a Berkovich Indenter Hardness Test may beexhibited by the anti-reflective coating and/or the article over anindentation depth of about 50 nm or greater or about 100 nm or greater(e.g., from about 100 nm to about 300 nm, from about 100 nm to about 400nm, from about 100 nm to about 500 nm, from about 100 nm to about 600nm, from about 200 nm to about 300 nm, from about 200 nm to about 400nm, from about 200 nm to about 500 nm, or from about 200 nm to about 600nm).

The anti-reflective coating 120 may have at least one layer made ofmaterial itself having a maximum hardness (as measured on the surface ofsuch a layer, e.g., a surface of the second high RI layer 130B of FIG.2A) of about 18 GPa or greater, about 19 GPa or greater, about 20 GPa orgreater, about 21 GPa or greater, about 22 GPa or greater, about 23 GPaor greater, about 24 GPa or greater, about 25 GPa or greater, and allhardness values therebetween, as measured by the Berkovich IndenterHardness Test over an indentation depth from about 100 nm to about 500nm. These measurements are made on a hardness test stack comprising thedesignated layer of the anti-reflective coating 120 at a physicalthickness of about 2 microns, as disposed on a substrate 110, tominimize the thickness-related hardness measurement effects describedearlier. The maximum hardness of such a layer may be in the range fromabout 18 GPa to about 26 GPa, as measured by the Berkovich IndenterHardness Test over an indentation depth from about 100 nm to about 500nm. Such maximum hardness values may be exhibited by the material of atleast one layer (e.g., the high RI layer(s) 130B, as shown in FIG. 2A)over an indentation depth of about 50 nm or greater or 100 nm or greater(e.g., from about 100 nm to about 300 nm, from about 100 nm to about 400nm, from about 100 nm to about 500 nm, from about 100 nm to about 600nm, from about 200 nm to about 300 nm, from about 200 nm to about 400nm, from about 200 nm to about 500 nm, or from about 200 nm to about 600nm). In one or more embodiments, the article 100 exhibits a hardnessthat is greater than the hardness of the substrate (which can bemeasured on the opposite surface from the anti-reflective surface).Similarly, hardness values may be exhibited by the material of at leastone layer (e.g., the high RI layer(s) 130B, as shown in FIG. 2A) over anindentation depth of about 50 nm or greater or about 100 nm or greater(e.g., from about 100 nm to about 300 nm, from about 100 nm to about 400nm, from about 100 nm to about 500 nm, from about 100 nm to about 600nm, from about 200 nm to about 300 nm, from about 200 nm to about 400nm, from about 200 nm to about 500 nm, or from about 200 nm to about 600nm). In addition, these hardness and/or maximum hardness valuesassociated with the at least one layer (e.g., the high RI layer(s) 130B)can also be observed at particular indentation depths (e.g., at 100 nm,200 nm, etc.) over the measured indentation depth ranges.

Optical interference between reflected waves from the interface betweenthe anti-reflective coating 120 and air, and from the interface betweenthe anti-reflective coating 120 and substrate 110, can lead to spectralreflectance and/or transmittance oscillations that create apparent colorin the article 100. As used herein, the term “transmittance” is definedas the percentage of incident optical power within a given wavelengthrange transmitted through a material (e.g., the article, the substrateor the optical film or portions thereof). The term “reflectance” issimilarly defined as the percentage of incident optical power within agiven wavelength range that is reflected from a material (e.g., thearticle, the substrate, or the optical film or portions thereof). In oneor more embodiments, the spectral resolution of the characterization ofthe transmittance and reflectance is less than 5 nm or 0.02 eV. Thecolor may be more pronounced in reflection. The angular color shifts inreflection with viewing angle due to a shift in the spectral reflectanceoscillations with incident illumination angle. Angular color shifts intransmittance with viewing angle are also due to the same shift in thespectral transmittance oscillation with incident illumination angle. Theobserved color and angular color shifts with incident illumination angleare often distracting or objectionable to device users, particularlyunder illumination with sharp spectral features, for example, underfluorescent lighting and some LED lighting. Angular color shifts intransmission may also play a factor in angular color shifts inreflection and vice versa. Factors in angular color shifts intransmission and/or reflection may also include angular color shifts dueto viewing angle or color shifts away from a certain white point thatmay be caused by material absorption (somewhat independent of angle)defined by a particular illuminant or test system.

The oscillations may be described in terms of amplitude. As used herein,the term “amplitude” includes the peak-to-valley change in reflectanceor transmittance. The phrase “average amplitude” includes thepeak-to-valley change in reflectance or transmittance averaged withinthe optical wavelength regime. As used herein, the “optical wavelengthregime” includes the wavelength range from about 400 nm to about 800 nm(and more specifically from about 450 nm to about 650 nm). According tosome embodiments, the optical wavelength range further includes theinfrared spectrum from 800 nm to 1000 nm.

The embodiments of this disclosure include an anti-reflective coating(e.g., anti-reflective coating 120 or optical film structure 120) toprovide improved optical performance, in terms of colorlessness and/orsmaller angular color shifts when viewed at varying incidentillumination angles from normal incidence under different illuminants.

One aspect of this disclosure pertains to an article that exhibitscolorlessness in reflectance and/or transmittance even when viewed atdifferent incident illumination angles under an illuminant. In one ormore embodiments, the article exhibits an angular color shift inreflectance and/or transmittance of about 5 or less, or about 2 or less,between a reference illumination angle and any incidental illuminationangles, in the ranges provided herein. As used herein, the phrase “colorshift” (angular or reference point) refers to the change in both a* andb*, under the International Commission on Illumination (CIE) L*, a*, b*colorimetry system in reflectance and/or transmittance. It should beunderstood that unless otherwise noted, the L* coordinate of thearticles described herein are the same at any angle or reference pointand do not influence color shift. For example, angular color shift maybe determined using the following Equation (1):

√((a* ₂ −a* ₁)²+(b* ₂ −b* ₁)²)  (1)

with a*₁, and b*₁ representing the a* and b* coordinates of the articlewhen viewed at a reference illumination angle (which may include normalincidence) and a*₂, and b*₂ representing the a* and b* coordinates ofthe article when viewed at an incident illumination angle, provided thatthe incident illumination angle is different from reference illuminationangle and in some cases differs from the reference illumination angle byabout 1 degree or more, 2 degrees or more, about 5 degrees or more,about 10 degrees or more, about 15 degrees or more, or about 20 degreesor more. In some instances, an angular color shift in reflectance and/ortransmittance of about 10 or less (e.g., 5 or less, 4 or less, 3 orless, or 2 or less) is exhibited by the article when viewed at variousincident illumination angles from a reference illumination angle, underan illuminant. In some instances the angular color shift in reflectanceand/or transmittance is about 1.9 or less, 1.8 or less, 1.7 or less, 1.6or less, 1.5 or less, 1.4 or less, 1.3 or less, 1.2 or less, 1.1 orless, 1 or less, 0.9 or less, 0.8 or less, 0.7 or less, 0.6 or less, 0.5or less, 0.4 or less, 0.3 or less, 0.2 or less, or 0.1 or less. In someembodiments, the angular color shift may be about 0. The illuminant caninclude standard illuminants as determined by the CIE, including Ailluminants (representing tungsten-filament lighting), B illuminants(daylight simulating illuminants), C illuminants (daylight simulatingilluminants), D series illuminants (representing natural daylight), andF series illuminants (representing various types of fluorescentlighting). In specific examples, the articles exhibit an angular colorshift in reflectance and/or transmittance of about 2 or less when viewedat an incident illumination angle from the reference illumination angleunder a CIE F2, F10, F11, F12 or D65 illuminant or more specificallyunder a CIE F2 illuminant.

The reference illumination angle may include normal incidence (i.e., 0degrees), or 5 degrees from normal incidence, 10 degrees from normalincidence, 15 degrees from normal incidence, 20 degrees from normalincidence, 25 degrees from normal incidence, 30 degrees from normalincidence, 35 degrees from normal incidence, 40 degrees from normalincidence, 50 degrees from normal incidence, 55 degrees from normalincidence, or 60 degrees from normal incidence, provided the differencebetween the reference illumination angle and the difference between theincident illumination angle and the reference illumination angle isabout 1 degree or more, 2 degrees or more, about 5 degrees or more,about 10 degrees or more, about 15 degrees or more, or about 20 degreesor more. The incident illumination angle may be, with respect to thereference illumination angle, in the range from about 5 degrees to about80 degrees, from about 5 degrees to about 75 degrees, from about 5degrees to about 70 degrees, from about 5 degrees to about 65 degrees,from about 5 degrees to about 60 degrees, from about 5 degrees to about55 degrees, from about 5 degrees to about 50 degrees, from about 5degrees to about 45 degrees, from about 5 degrees to about 40 degrees,from about 5 degrees to about 35 degrees, from about 5 degrees to about30 degrees, from about 5 degrees to about 25 degrees, from about 5degrees to about 20 degrees, from about 5 degrees to about 15 degrees,and all ranges and sub-ranges therebetween, away from normal incidence.The article may exhibit the angular color shifts in reflectance and/ortransmittance described herein at and along all the incidentillumination angles in the range from about 2 degrees to about 80degrees, or from about 5 degrees to about 80 degrees, or from about 10degrees to about 80 degrees, or from about 15 degrees to about 80degrees, or from about 20 degrees to about 80 degrees, when thereference illumination angle is normal incidence. In some embodiments,the article may exhibit the angular color shifts in reflectance and/ortransmittance described herein at and along all the incidentillumination angles in the range from about 2 degrees to about 80degrees, or from about 5 degrees to about 80 degrees, or from about 10degrees to about 80 degrees, or from about 15 degrees to about 80degrees, or from about 20 degrees to about 80 degrees, when thedifference between the incident illumination angle and the referenceillumination angle is about 1 degree or more, 2 degrees or more, about 5degrees or more, about 10 degrees or more, about 15 degrees or more, orabout 20 degrees or more. In one example, the article may exhibit anangular color shift in reflectance and/or transmittance of 2 or less atany incident illumination angle in the range from about 2 degrees toabout 60 degrees, from about 5 degrees to about 60 degrees, or fromabout 10 degrees to about 60 degrees away from a reference illuminationangle equal to normal incidence. In other examples, the article mayexhibit an angular color shift in reflectance and/or transmittance of 2or less when the reference illumination angle is 10 degrees and theincident illumination angle is any angle in the range from about 12degrees to about 60 degrees, from about 15 degrees to about 60 degrees,or from about 20 degrees to about 60 degrees away from the referenceillumination angle.

In some embodiments, the angular color shift may be measured at allangles between a reference illumination angle (e.g., normal incidence)and an incident illumination angle in the range from about 20 degrees toabout 80 degrees. In other words, the angular color shift may bemeasured and may be less than about 5, or less than about 2, at allangles in the range from about 0 degrees to about 20 degrees, from about0 degrees to about 30 degrees, from about 0 degrees to about 40 degrees,from about 0 degrees to about 50 degrees, from about 0 degrees to about60 degrees, or from about 0 degrees to about 80 degrees.

In one or more embodiments, the article 100 exhibits a color in the CIEL*, a*, b* colorimetry system in reflectance and/or transmittance suchthat the distance or reference point color shift between thetransmittance color or reflectance coordinates from a reference point isless than about 5, or less than about 2, under an illuminant (which caninclude standard illuminants as determined by the CIE, including Ailluminants (representing tungsten-filament lighting), B illuminants(daylight simulating illuminants), C illuminants (daylight simulatingilluminants), D series illuminants (representing natural daylight), andF series illuminants (representing various types of fluorescentlighting). In specific examples, the articles exhibit a color shift inreflectance and/or transmittance of about 2 or less when viewed at anincident illumination angle from the reference illumination angle undera CIE F2, F10, F11, F12 or D65 illuminant or more specifically under aCIE F2 illuminant. Stated another way, the article may exhibit atransmittance color (or transmittance color coordinates) and/or areflectance color (or reflectance color coordinates) measured at theanti-reflective surface 122 having a reference point color shift of lessthan about 2 from a reference point, as defined herein. Unless otherwisenoted, the transmittance color or transmittance color coordinates aremeasured on two surfaces of the article including at the anti-reflectivesurface 122 and the opposite bare surface of the article (i.e., 114).Unless otherwise noted, the reflectance color or reflectance colorcoordinates are measured on only the anti-reflective surface 122 of thearticle.

In one or more embodiments, the reference point may be the origin (0, 0)in the CIE L*, a*, b* colorimetry system (or the color coordinates a*=0,b*=0), color coordinates (a*=−2, b*=−2) or the transmittance orreflectance color coordinates of the substrate. It should be understoodthat unless otherwise noted, the L* coordinate of the articles describedherein are the same as the reference point and do not influence colorshift. Where the reference point color shift of the article is definedwith respect to the substrate, the transmittance color coordinates ofthe article are compared to the transmittance color coordinates of thesubstrate and the reflectance color coordinates of the article arecompared to the reflectance color coordinates of the substrate.

In one or more specific embodiments, the reference point color shift ofthe transmittance color and/or the reflectance color may be less than 1or even less than 0.5. In one or more specific embodiments, thereference point color shift for the transmittance color and/or thereflectance color may be 1.8, 1.6, 1.4, 1.2, 0.8, 0.6, 0.4, 0.2, 0 andall ranges and sub-ranges therebetween. Where the reference point is thecolor coordinates a*=0, b*=0, the reference point color shift iscalculated by Equation (2):

reference point color shift=√((a* _(article))²(b* _(article))²).  (2)

Where the reference point is the color coordinates a*=−2, b*=−2, thereference point color shift is calculated by Equation (3):

reference point color shift=√((a* _(article)+2)²+(b*_(article)+2)²).  (3)

Where the reference point is the color coordinates of the substrate, thereference point color shift is calculated by Equation (4):

reference point color shift=√((a* _(article) −a* _(substrate))²+(b*_(article) −b* _(substrate))²)  (4)

In some embodiments, the article 100 may exhibit a transmittance color(or transmittance color coordinates) and a reflectance color (orreflectance color coordinates) such that the reference point color shiftis less than 2 when the reference point is any one of the colorcoordinates of the substrate, the color coordinates a*=0, b*=0 and thecolor coordinates a*=−2, b*=−2.

In some embodiments, the article 100 may exhibit a b* value inreflectance (as measured at the anti-reflective surface 122 only) in therange from about −10 to about +2, from about −7 to about 0, from about−6 to about −1, from about −6 to about 0, or from about −4 to about 0,in the CIE L*, a*, b* colorimetry system at a near-normal incident angle(i.e., at about 0 degrees, or within 10 degrees of normal). In otherimplementations, the article 100 may exhibit a b* value in reflectance(as measured at the anti-reflective surface 122 only) in the range fromabout −10 to about +10, from about −8 to about +8, or from about −5 toabout +5, in the CIE L*, a*, b* colorimetry system at all incidenceillumination angles in the range from about 0 to about 60 degrees (orfrom about 0 degrees to about 40 degrees, or from about 0 degrees toabout 30 degrees).

In some embodiments, the article 100 may exhibit a b* value intransmittance (as measured at the anti-reflective surface and theopposite bare surface of the article) in the range from about −2 toabout 2, from about −1 to about 2, from about −0.5 to about 2, fromabout 0 to about 2, from about 0 to about 1, from about −2 to about 0.5,from about −2 to about 1, from about −1 to about 1, or from about 0 toabout 0.5, in the CIE L*, a*, b* colorimetry system at a near-normalincident angle (i.e., at about 0 degrees, or within 10 degrees ofnormal). In other implementations, the article may exhibit a b* value intransmittance in the range from about −2 to about 2, from about −1 toabout 2, from about −0.5 to about 2, from about 0 to about 2, from about0 to about 1, from about −2 to about 0.5, from about −2 to about 1, fromabout −1 to about 1, or from about 0 to about 0.5, in the CIE L*, a*, b*colorimetry system for all incidence illumination angles in the rangefrom about 0 to about 60 degrees (or from about 0 degrees to about 40degrees, or from about 0 degrees to about 30 degrees).

In some embodiments, the article 100 may exhibit an a* value intransmittance (as measured at the anti-reflective surface and theopposite bare surface of the article) in the range from about −2 toabout 2, from about −1 to about 2, from about −0.5 to about 2, fromabout 0 to about 2, from about 0 to about 1, from about −2 to about 0.5,from about −2 to about 1, from about −1 to about 1, or from about 0 toabout 0.5, in the CIE L*, a*, b* colorimetry system at a near-normalincident angle (i.e., at about 0 degrees, or within 10 degrees ofnormal). In other implementations, the article may exhibit an a* valuein transmittance in the range from about −2 to about 2, from about −1 toabout 2, from about −0.5 to about 2, from about 0 to about 2, from about0 to about 1, from about −2 to about 0.5, from about −2 to about 1, fromabout −1 to about 1, or from about 0 to about 0.5, in the CIE L*, a*, b*colorimetry system for all incidence illumination angles in the rangefrom about 0 to about 60 degrees (or from about 0 degrees to about 40degrees or from about 0 degrees to about 30 degrees).

In some embodiments, the article 100 exhibits a* and/or b* values intransmittance (at the anti-reflective surface and the opposite baresurface) in the range from about −1.5 to about 1.5 (e.g., −1.5 to −1.2,−1.5 to −1, −1.2 to 1.2, −1 to 1, −1 to 0.5, or −1 to 0) at incidentillumination angles in the range from about 0 degrees to about 60degrees under illuminants D65, A, and F2.

In some embodiments, the article 100 exhibits an a* value in reflectance(at only the anti-reflective surface) in the range from about −10 toabout +5, −5 to about +5 (e.g., −4.5 to +4.5, −4.5 to +1.5, −3 to 0,−2.5 to −0.25), or from about −4 to +4, at a near-normal incident angle(i.e., at about 0 degrees, or within 10 degrees of normal) in the CIEL*, a*, b* colorimetry system. In other embodiments, the article 100exhibits an a* value in reflectance (at only the anti-reflectivesurface) in the range from about −5 to about +15 (e.g., −4.5 to +14) orfrom about −3 to +13 at incident illumination angles in the range fromabout 0 degrees to about 60 degrees in the CIE L*, a*, b* colorimetrysystem.

The article 100 of one or more embodiments, or the anti-reflectivesurface 122 of one or more articles, may exhibit a photopic averagelight transmittance of about 94% or greater (e.g., about 94% or greater,about 95% or greater, about 96% or greater, about 96.5% or greater,about 97% or greater, about 97.5% or greater, about 98% or greater,about 98.5% or greater or about 99% or greater) over the opticalwavelength regime in the range from about 400 nm to about 800 nm. Insome embodiments, the article 100, or the anti-reflective surface 122 ofone or more articles, may exhibit an average light reflectance of about2% or less (e.g., about 1.5% or less, about 1% or less, about 0.75% orless, about 0.5% or less, or about 0.25% or less) over the opticalwavelength regime in the range from about 400 nm to about 800 nm. Theselight transmittance and light reflectance values may be observed overthe entire optical wavelength regime or over selected ranges of theoptical wavelength regime (e.g., a 100 nm wavelength range, 150 nmwavelength range, a 200 nm wavelength range, a 250 nm wavelength range,a 280 nm wavelength range, or a 300 nm wavelength range, within theoptical wavelength regime). In some embodiments, these light reflectanceand transmittance values may be a total reflectance or totaltransmittance (taking into account reflectance or transmittance on boththe anti-reflective surface 122 and the opposite major surface, 114).Unless otherwise specified, the average reflectance or transmittance ismeasured at an incident illumination angle of 0 degrees (however, suchmeasurements may be provided at incident illumination angles of 45degrees or 60 degrees).

The article 100 of one or more embodiments, or the anti-reflectivesurface 122 of one or more articles, may exhibit an average lighttransmittance of about 87% or greater (e.g., about 87% or greater, about88% or greater, about 89% or greater, about 90% or greater, about 91% orgreater, about 92% or greater, about 93% or greater, about 94% orgreater or about 95% or greater) over the optical wavelength regime inthe infrared spectrum from about 800 nm to about 1000 nm, from about 900nm to 1000 nm or from 930 nm to 950 nm. In these embodiments, thearticle 100, or the anti-reflective surface 122 of one or more articles,may exhibit an average light reflectance of about 2% or less, about 1%or less, or about 0.5% or less (e.g., about 1.5% or less, about 1% orless, about 0.75% or less, about 0.5% or less, or about 0.25% or less)over the optical wavelength regime in the range from about 400 nm toabout 800 nm. These light transmittance and light reflectance values maybe observed over the entire optical wavelength regime or over selectedranges of the optical wavelength regime (e.g., a 100 nm wavelengthrange, a 150 nm wavelength range, a 200 nm wavelength range, a 250 nmwavelength range, a 280 nm wavelength range, or a 300 nm wavelengthrange, within the optical wavelength regime). In some of theseembodiments, the light reflectance and transmittance values may be atotal reflectance or total transmittance (taking into accountreflectance or transmittance on both the anti-reflective surface 122 andthe opposite major surface, 114). Unless otherwise specified, theaverage reflectance or transmittance of these embodiments is measured atan incident illumination angle of 0 degrees (however, such measurementsmay be provided at incident illumination angles of 45 degrees or 60degrees).

In some embodiments, the article 100 of one or more embodiments, or theanti-reflective surface 122 of one or more articles, may exhibit avisible photopic average reflectance of about 1% or less, about 0.9% orless, about 0.8% or less, about 0.7% or less, about 0.6% or less, about0.5% or less, about 0.4% or less, about 0.3% or less, or about 0.2% orless, over the optical wavelength regime. These photopic averagereflectance values may be exhibited at incident illumination angles inthe range from about 0° to about 20°, from about 0° to about 40°, orfrom about 0° to about 60°. As used herein, “photopic averagereflectance” mimics the response of the human eye by weighting thereflectance versus wavelength spectrum according to the human eye'ssensitivity. Photopic average reflectance may also be defined as theluminance, or tristimulus Y value of reflected light, according to knownconventions for example CIE color space conventions. The photopicaverage reflectance is defined in Equation (5) as the spectralreflectance, R(λ), multiplied by the illuminant spectrum, I(λ), and theCIE's color matching function, γ(λ), related to the eye's spectralresponse:

R _(p)

=∫_(380 nm) ^(720 nm) R(λ)×I(λ)×γ(λ)dλ.  (5)

In some embodiments, the anti-reflective surface 122 of one or morearticles (i.e., when measuring the anti-reflective surface 122 onlythrough a single-sided measurement) may exhibit a visible photopicaverage reflectance of about 2% or less, about 1.8% or less, about 1.5%or less, about 1.2% or less, about 1% or less, about 0.9% or less, about0.7% or less, about 0.5% or less, about 0.45% or less, about 0.4% orless, about 0.35% or less, about 0.3% or less, about 0.25% or less, orabout 0.2% or less. In such “single-sided” measurements as described inthis disclosure, the reflectance from the second major surface (e.g.,surface 114 shown in FIG. 1) is removed by coupling this surface to anindex-matched absorber. In some cases, the visible photopic averagereflectance ranges are exhibited while simultaneously exhibiting amaximum reflectance color shift, over the entire incident illuminationangle range from about 5 degrees to about 60 degrees (with the referenceillumination angle being normal incidence) using D65 illumination, ofless than about 5.0, less than about 4.0, less than about 3.0, less thanabout 2.0, less than about 1.5, or less than about 1.25. These maximumreflectance color shift values represent the lowest color point valuemeasured at any angle from about 5 degrees to about 60 degrees fromnormal incidence, subtracted from the highest color point value measuredat any angle in the same range. The values may represent a maximumchange in a* value (a*_(highest)−a*_(lowest)), a maximum change in b*value (b*_(highest)−b*_(lowest)), a maximum change in both a* and b*values, or a maximum change in the quantity√((a*_(highest)−a*_(lowest))²+(b*_(highest)−b*_(lowest))²).

Substrate

The substrate 110 may include an inorganic oxide material and mayinclude an amorphous substrate, a crystalline substrate or a combinationthereof. In one or more embodiments, the substrate exhibits a refractiveindex in the range from about 1.45 to about 1.55, e.g., 1.45, 1.46,1.47, 1.48, 1.49, 1.50, 1.51, 1.52, 1.53, 1.54, 1.55, and all refractiveindices therebetween.

Suitable substrates 110 may exhibit an elastic modulus (or Young'smodulus) in the range from about 30 GPa to about 120 GPa. In someinstances, the elastic modulus of the substrate may be in the range fromabout 30 GPa to about 110 GPa, from about 30 GPa to about 100 GPa, fromabout 30 GPa to about 90 GPa, from about 30 GPa to about 80 GPa, fromabout 30 GPa to about 70 GPa, from about 40 GPa to about 120 GPa, fromabout 50 GPa to about 120 GPa, from about 60 GPa to about 120 GPa, fromabout 70 GPa to about 120 GPa, and all ranges and sub-rangestherebetween. The Young's modulus values for the substrate itself asrecited in this disclosure refer to values as measured by a resonantultrasonic spectroscopy technique of the general type set forth in ASTME2001-13, titled “Standard Guide for Resonant Ultrasound Spectroscopyfor Defect Detection in Both Metallic and Non-metallic Parts.”

In one or more embodiments, the amorphous substrate may include glass,which may be strengthened or non-strengthened. Examples of suitableglass include soda lime glass, alkali aluminosilicate glass, alkalicontaining borosilicate glass and alkali aluminoborosilicate glass. Insome variants, the glass may be free of lithia. In one or morealternative embodiments, the substrate 110 may include crystallinesubstrates, for example, glass-ceramic, or ceramic, substrates (whichmay be strengthened or non-strengthened), or may include a singlecrystal structure, for example, sapphire. In one or more specificembodiments, the substrate 110 includes an amorphous base (e.g., glass)and a crystalline cladding (e.g., sapphire layer, a polycrystallinealumina layer and/or or a spinel (MgAl₂O₄) layer).

The substrate 110 may be substantially planar or sheet-like, althoughother embodiments may utilize a curved or otherwise shaped or sculptedsubstrate. The substrate 110 may be substantially optically clear,transparent and free from light scattering. In such embodiments, thesubstrate may exhibit an average light transmission over the opticalwavelength regime of about 85% or greater, about 86% or greater, about87% or greater, about 88% or greater, about 89% or greater, about 90% orgreater, about 91% or greater or about 92% or greater. In one or morealternative embodiments, the substrate 110 may be opaque or exhibit anaverage light transmission over the optical wavelength regime of lessthan about 10%, less than about 9%, less than about 8%, less than about7%, less than about 6%, less than about 5%, less than about 4%, lessthan about 3%, less than about 2%, less than about 1%, or less thanabout 0%. In some embodiments, these light reflectance and transmittancevalues may be a total reflectance or total transmittance (taking intoaccount reflectance or transmittance on both major surfaces of thesubstrate) or may be observed on a single side of the substrate (i.e.,on the anti-reflective surface 122 only, without taking into account theopposite surface). Unless otherwise specified, the average reflectanceor transmittance is measured at an incident illumination angle of 0degrees (however, such measurements may be provided at incidentillumination angles of 45 degrees or 60 degrees). The substrate 110 mayoptionally exhibit a color, for example white, black, red, blue, green,yellow, orange, etc.

Additionally or alternatively, the physical thickness of the substrate110 may vary along one or more of its dimensions for aesthetic and/orfunctional reasons. For example, the edges of the substrate 110 may bethicker as compared to more central regions of the substrate 110. Thelength, width and physical thickness dimensions of the substrate 110 mayalso vary according to the application or use of the article 100.

The substrate 110 may be provided using a variety of differentprocesses. For instance, where the substrate 110 includes an amorphoussubstrate, for example, glass, various forming methods can include floatglass processes, rolling processes, updraw processes, and down-drawprocesses, for example fusion draw and slot draw.

Once formed, a substrate 110 may be strengthened to form a strengthenedsubstrate. As used herein, the term “strengthened substrate” may referto a substrate that has been chemically strengthened, for examplethrough ion-exchange of larger ions for smaller ions in the surface ofthe substrate. However, other strengthening methods known in the art,for example thermal tempering, or utilizing a mismatch of thecoefficient of thermal expansion between portions of the substrate tocreate compressive stress and central tension regions, may be utilizedto form strengthened substrates.

Where the substrate is chemically strengthened by an ion exchangeprocess, the ions in the surface layer of the substrate are replacedby—or exchanged with—larger ions having the same valence or oxidationstate. Ion exchange processes are typically carried out by immersing asubstrate in a molten salt bath containing the larger ions to beexchanged with the smaller ions in the substrate. It will be appreciatedby those skilled in the art that parameters for the ion exchangeprocess, including, but not limited to, bath composition andtemperature, immersion time, the number of immersions of the substratein a salt bath (or baths), use of multiple salt baths, and anyadditional steps (e.g., annealing, washing, and the like) are generallydetermined by the composition of the substrate, the desired compressivestress (CS), and the desired depth of compressive stress (CS) layer (ordepth of layer) of the substrate that result from the strengtheningoperation. By way of example, ion exchange of alkali metal-containingglass substrates may be achieved by immersion in at least one moltenbath containing a salt for example, but not limited to, nitrates,sulfates, and chlorides of the larger alkali metal ion. The temperatureof the molten salt bath typically is in a range from about 380° C. up toabout 450° C., while immersion times range from about 15 minutes up toabout 40 hours. However, temperatures and immersion times different fromthose described above may also be used.

In addition, non-limiting examples of ion exchange processes in whichglass substrates are immersed in multiple ion exchange baths, withwashing and/or annealing steps between immersions, are described in U.S.patent application Ser. No. 12/500,650, filed Jul. 10, 2009, by DouglasC. Allan et al., entitled “Glass with Compressive Surface for ConsumerApplications”, claiming priority from U.S. Provisional PatentApplication No. 61/079,995, filed Jul. 11, 2008, in which glasssubstrates are strengthened by immersion in multiple, successive, ionexchange treatments in salt baths of different concentrations; and U.S.Pat. No. 8,312,739, by Christopher M. Lee et al., issued on Nov. 20,2012, and entitled “Dual Stage Ion Exchange for Chemical Strengtheningof Glass,” claiming priority from U.S. Provisional Patent ApplicationNo. 61/084,398, filed Jul. 29, 2008, in which glass substrates arestrengthened by ion exchange in a first bath diluted with an effluention, followed by immersion in a second bath having a smallerconcentration of the effluent ion than the first bath. The contents ofU.S. patent application Ser. No. 12/500,650 and U.S. Pat. No. 8,312,739are incorporated herein by reference in their entirety.

The degree of chemical strengthening achieved by ion exchange may bequantified based on the parameters of central tension (CT), peak CS,depth of compression (DOC, which is the point along the thicknesswherein compression changes to tension), and depth of ion layer (DOL).Peak CS, which is a maximum observed compressive stress, may be measurednear the surface of the substrate 110 or within the strengthened glassat various depths. A peak CS value may include the measured CS at thesurface (CS_(s)) of the strengthened substrate. In other embodiments,the peak CS is measured below the surface of the strengthened substrate.Compressive stress (including surface CS) is measured by surface stressmeter (FSM) using commercially available instruments such as theFSM-6000, manufactured by Orihara Industrial Co., Ltd. (Japan). Surfacestress measurements rely upon the accurate measurement of the stressoptical coefficient (SOC), which is related to the birefringence of theglass. SOC in turn is measured according to Procedure C (Glass DiscMethod) described in ASTM standard C770-16, entitled “Standard TestMethod for Measurement of Glass Stress-Optical Coefficient,” thecontents of which are incorporated herein by reference in theirentirety. As used herein, DOC means the depth at which the stress in thechemically strengthened alkali aluminosilicate glass article describedherein changes from compressive to tensile. DOC may be measured by FSMor a scattered light polariscope (SCALP) depending on the ion exchangetreatment. Where the stress in the glass article is generated byexchanging potassium ions into the glass article, FSM is used to measureDOC. Where the stress is generated by exchanging sodium ions into theglass article, SCALP is used to measure DOC. Where the stress in theglass article is generated by exchanging both potassium and sodium ionsinto the glass, the DOC is measured by SCALP, since it is believed theexchange depth of sodium indicates the DOC and the exchange depth ofpotassium ions indicates a change in the magnitude of the compressivestress (but not the change in stress from compressive to tensile); theexchange depth of potassium ions in such glass articles is measured byFSM. Maximum CT values are measured using a scattered light polariscope(SCALP) technique known in the art. Refracted near-field (RNF) method orSCALP may be used to measure (graph, depict visually, or otherwise mapout) the complete stress profile. When the RNF method is utilized tomeasure the stress profile, the maximum CT value provided by SCALP isutilized in the RNF method. In particular, the stress profile measuredby RNF is force balanced and calibrated to the maximum CT value providedby a SCALP measurement. The RNF method is described in U.S. Pat. No.8,854,623, entitled “Systems and methods for measuring a profilecharacteristic of a glass sample”, which is incorporated herein byreference in its entirety. In particular, the RNF method includesplacing the glass article adjacent to a reference block, generating apolarization-switched light beam that is switched between orthogonalpolarizations at a rate of from 1 Hz to 50 Hz, measuring an amount ofpower in the polarization-switched light beam and generating apolarization-switched reference signal, wherein the measured amounts ofpower in each of the orthogonal polarizations are within 50% of eachother. The method further includes transmitting thepolarization-switched light beam through the glass sample and referenceblock for different depths into the glass sample, then relaying thetransmitted polarization-switched light beam to a signal photodetectorusing a relay optical system, with the signal photodetector generating apolarization-switched detector signal. The method also includes dividingthe detector signal by the reference signal to form a normalizeddetector signal and determining the profile characteristic of the glasssample from the normalized detector signal.

In some embodiments, a strengthened substrate 110 can have a peak CS of250 MPa or greater, 300 MPa or greater, 400 MPa or greater, 450 MPa orgreater, 500 MPa or greater, 550 MPa or greater, 600 MPa or greater, 650MPa or greater, 700 MPa or greater, 750 MPa or greater, or 800 MPa orgreater. The strengthened substrate may have a DOC of 10 μm or greater,15 μm or greater, 20 μm or greater (e.g., 25 μm, 30 μm, 35 μm, 40 μm, 45μm, 50 μm, or greater) and/or a CT of 10 MPa or greater, 20 MPa orgreater, 30 MPa or greater, 40 MPa or greater (e.g., 42 MPa, 45 MPa, or50 MPa or greater) but less than 100 MPa (e.g., 95, 90, 85, 80, 75, 70,65, 60, 55 MPa or less). In one or more specific embodiments, thestrengthened substrate has one or more of the following: a peak CSgreater than 500 MPa, a DOC greater than 15 μm, and a CT greater than 18MPa.

Example glasses that may be used in the substrate may include alkalialuminosilicate glass compositions or alkali aluminoborosilicate glasscompositions, though other glass compositions are contemplated. Suchglass compositions are capable of being chemically strengthened by anion exchange process. One example glass composition comprises SiO₂, B₂O₃and Na₂O, where (SiO₂+B₂O₃)≥66 mol. %, and Na₂O≥9 mol. %. In someembodiments, the glass composition includes about 6 wt. % aluminum oxideor more. In some embodiments, the substrate includes a glass compositionwith one or more alkaline earth oxides, such that a content of alkalineearth oxides is about 5 wt. % or more. Suitable glass compositions, insome embodiments, further comprise at least one of K₂O, MgO, or CaO. Insome embodiments, the glass compositions used in the substrate cancomprise 61-75 mol. % SiO₂; 7-15 mol. % Al₂O₃; 0-12 mol. % B₂O₃; 9-21mol. % Na₂O; 0-4 mol. % K₂O; 0-7 mol. % MgO; and 0-3 mol. % CaO.

A further example glass composition suitable for the substratecomprises: 60-70 mol. % SiO₂; 6-14 mol. % Al₂O₃; 0-15 mol. % B₂O₃; 0-15mol. % Li₂O; 0-20 mol. % Na₂O; 0-10 mol. % K₂O; 0-8 mol. % MgO; 0-10mol. % CaO; 0-5 mol. % ZrO₂; 0-1 mol. % SnO₂; 0-1 mol. % CeO₂; less than50 ppm As₂O₃; and less than 50 ppm Sb₂O₃; where 12 mol.%≤(Li₂O+Na₂O+K₂O)≤20 mol. % and 0 mol. %≤(MgO+CaO)≤10 mol. %.

A still further example glass composition suitable for the substratecomprises: 63.5-66.5 mol. % SiO₂; 8-12 mol. % Al₂O₃; 0-3 mol. % B₂O₃;0-5 mol. % Li₂O; 8-18 mol. % Na₂O; 0-5 mol. % K₂O; 1-7 mol. % MgO; 0-2.5mol. % CaO; 0-3 mol. % ZrO₂; 0.05-0.25 mol. % SnO₂; 0.05-0.5 mol. %CeO₂; less than 50 ppm As₂O₃; and less than 50 ppm Sb₂O₃; where 14 mol.%≤(Li₂O+Na₂O+K₂O) 18 mol. % and 2 mol. %≤(MgO+CaO)≤7 mol. %.

In some embodiments, an alkali aluminosilicate glass compositionsuitable for the substrate 110 comprises alumina, at least one alkalimetal and, in some embodiments, greater than 50 mol. % SiO₂, in otherembodiments 58 mol. % SiO₂ or more, and in still other embodiments 60mol. % SiO₂ or more, wherein the ratio (Al₂O₃+B₂O₃)/Σmodifiers (i.e.,sum of modifiers) is greater than 1, wherein the ratio of thesecomponents are expressed in mol. % and the modifiers are alkali metaloxides. This glass composition, in particular embodiments, comprises:58-72 mol. % SiO₂; 9-17 mol. % Al₂O₃; 2-12 mol. % B₂O₃; 8-16 mol. %Na₂O; and 0-4 mol. % K₂O, wherein the ratio (Al₂O₃+B₂O₃)/Σmodifiers(i.e., sum of modifiers) is greater than 1.

In some embodiments, the substrate 110 may include an alkalialuminosilicate glass composition comprising: 64-68 mol. % SiO₂; 12-16mol. % Na₂O; 8-12 mol. % Al₂O₃; 0-3 mol. % B₂O₃; 2-5 mol. % K₂O; 4-6mol. % MgO; and 0-5 mol. % CaO, wherein: 66 mol. %≤SiO₂+B₂O₃+CaO≤69 mol.%; Na₂O+K₂O+B₂O₃+MgO+CaO+SrO>10 mol. %; 5 mol. %≤MgO+CaO+SrO≤8 mol. %;(Na₂O+B₂O₃)—Al₂O₃≤2 mol. %; 2 mol. %≤Na₂O—Al₂O₃≤6 mol. %; and 4 mol.%≤(Na₂O+K₂O)—Al₂O₃≤10 mol. %.

In some embodiments, the substrate 110 may comprise an alkalialuminosilicate glass composition comprising: 2 mol. % or more of Al₂O₃and/or ZrO₂, or 4 mol. % or more of Al₂O₃ and/or ZrO₂.

Where the substrate 110 includes a crystalline substrate, the substratemay include a single crystal, which may include Al₂O₃. Such singlecrystal substrates are referred to as sapphire. Other suitable materialsfor a crystalline substrate include polycrystalline alumina layer and/orspinel (MgAl₂O₄).

Optionally, the crystalline substrate 110 may include a glass-ceramicsubstrate, which may be strengthened or non-strengthened. Examples ofsuitable glass-ceramics may include Li₂O—Al₂O₃—SiO₂ system (i.e.,LAS-System) glass-ceramics, MgO—Al₂O₃—SiO₂ system (i.e., MAS-System)glass-ceramics, and/or glass-ceramics that include a predominant crystalphase including β-quartz solid solution, β-spodumene ss, cordierite, andlithium disilicate. The glass-ceramic substrates may be strengthenedusing the chemical strengthening processes disclosed herein. In one ormore embodiments, MAS-System glass-ceramic substrates may bestrengthened in Li₂SO₄ molten salt, whereby an exchange of 2Li⁺ for Mg²⁺can occur.

The substrate 110, according to one or more embodiments, can have aphysical thickness ranging from about 50 μm to about 5 mm. Examplesubstrate 110 physical thicknesses range from about 50 μm to about 500μm (e.g., 50, 100, 200, 300, 400 or 500 μm). Further example substrate110 physical thicknesses range from about 500 μm to about 1000 μm (e.g.,500, 600, 700, 800, 900 or 1000 μm). The substrate 110 may have aphysical thickness greater than about 1 mm (e.g., about 2, 3, 4, or 5mm). In one or more specific embodiments, the substrate 110 may have aphysical thickness of 2 mm or less or less than 1 mm. The substrate 110may be acid polished or otherwise treated to remove or reduce the effectof surface flaws.

Anti-Reflective Coating

As shown in FIG. 1, the anti-reflective coating 120 of the article 100may include a plurality of layers 120A, 120B, 120C. In some embodiments,one or more layers may be disposed on the opposite side of the substrate110 from the anti-reflective coating 120 (i.e., on major surface 114)(not shown). In some embodiments of the article 100, layer 120C, asshown in FIG. 1, can serve as a capping layer (e.g., capping layer 131as shown in FIGS. 2A and 2B and described in the sections below).

The physical thickness of the anti-reflective coating 120 may be in therange from about 50 nm to less than 500 nm. In some instances, thephysical thickness of the anti-reflective coating 120 may be in therange from about 10 nm to less than 500 nm, from about 50 nm to lessthan 500 nm, from about 75 nm to less than 500 nm, from about 100 nm toless than 500 nm, from about 125 nm to less than 500 nm, from about 150nm to less than 500 nm, from about 175 nm to less than 500 nm, fromabout 200 nm to less than 500 nm, from about 225 nm to less than 500 nm,from about 250 nm to less than 500 nm, from about 300 nm to less than500 nm, from about 350 nm to less than 500 nm, from about 400 nm to lessthan 500 nm, from about 450 nm to less than 500 nm, from about 200 nm toabout 450 nm, and all ranges and sub-ranges therebetween. For example,the physical thickness of the anti-reflective coating 120 may be from 10nm to 490 nm, or from 10 nm to 480 nm, or from 10 nm to 475 nm, or from10 nm to 460 nm, or from 10 nm to 450 nm, or from 10 nm to 430 nm, orfrom 10 nm to 425 nm, or from 10 nm to 420 nm, or from 10 nm to 410 nm,or from 10 nm to 400 nm, or from 10 nm to 350 nm, or from 10 nm to 300nm, or from 10 nm to 250 nm, or from 10 nm to 225 nm, or from 10 nm to200 nm, or from 15 nm to 490 nm, or from 20 nm to 490 nm, or from 25 nmto 490 nm, or from 30 nm to 490 nm, or from 35 nm to 490 nm, or from 40nm to 490 nm, or from 45 nm to 490 nm, or from 50 nm to 490 nm, or from55 nm to 490 nm, or from 60 nm to 490 nm, or from 65 nm to 490 nm, orfrom 70 nm to 490 nm, or from 75 nm to 490 nm, or from 80 nm to 490 nm,or from 85 nm to 490 nm, or from 90 nm to 490 nm, or from 95 nm to 490nm, or from 100 nm to 490 nm, or from 10 nm to 485 nm, or from 15 nm to480 nm, or from 20 nm to 475 nm, or from 25 nm to 460 nm, or from 30 nmto 450 nm, or from 35 nm to 440 nm, or from 40 nm to 430 nm, or from 50nm to 425 nm, or from 55 nm to 420 nm, or from 60 nm to 410 nm, or from70 nm to 400 nm, or from 75 nm to 400 nm, or from 80 nm to 390 nm, orfrom 90 nm to 380 nm, or from 100 nm to 375 nm, or from 110 nm to 370nm, or from 120 nm to 360 nm, or from 125 nm to 350 nm, or from 130 nmto 325 nm, or from 140 nm to 320 nm, or from 150 nm to 310 nm, or from160 nm to 300 nm, or from 170 nm to 300 nm, or from 175 nm to 300 nm, orfrom 180 nm to 290 nm, or from 190 nm to 280 nm, or from 200 nm to 275nm.

In one or more embodiments, as shown in FIGS. 2A and 2B, theanti-reflective coating 120 of the article 100 may include a period 130comprising two or more layers. In one or more embodiments, the two ormore layers may be characterized as having different refractive indicesfrom each another. In some embodiments, the period 130 includes a firstlow RI layer 130A and a second high RI layer 130B. The difference in therefractive index of the first low RI layer 130A and the second high RIlayer 130B may be about 0.01 or greater, 0.05 or greater, 0.1 or greateror even 0.2 or greater. In some implementations, the refractive index ofthe low RI layer(s) 130A is within the refractive index of the substrate110 such that the refractive index of the low RI layer(s) 130A is lessthan about 1.8, and the high RI layer(s) 130B have a refractive indexthat is greater than 1.8.

As shown in FIG. 2A, the anti-reflective coating 120 may include aplurality of periods (130). A single period includes a first low RIlayer 130A and a second high RI layer 130B, such that when a pluralityof periods are provided, the first low RI layer 130A (designated forillustration as “L”) and the second high RI layer 130B (designated forillustration as “H”) alternate in the following sequence of layers:L/H/L/H or H/L/H/L, such that the first low RI layer and the second highRI layer appear to alternate along the physical thickness of theanti-reflective coating 120. In the example in FIG. 2A, theanti-reflective coating 120 includes three periods 130 such that thereare three pairs of low RI and high RI layers 130A and 130B,respectively. In the example in FIG. 2B, the anti-reflective coating 120includes two periods 130 such that there are two pairs of low RI andhigh RI layers 130A and 130B, respectively. In some embodiments, theanti-reflective coating 120 may include up to 25 periods. For example,the anti-reflective coating 120 may include from about 2 to about 20periods, from about 2 to about 15 periods, from about 2 to about 10periods, from about 2 to about 12 periods, from about 3 to about 8periods, from about 3 to about 6 periods.

In the embodiments of the article 100 shown in FIGS. 2A and 2B, theanti-reflective coating 120 may include an additional capping layer 131,which may include a lower refractive index material than the second highRI layer 130B. In some implementations, the refractive index of thecapping layer 131 is the same or substantially the same as therefractive index of the low RI layers 130A.

As used herein, the terms “low RI” and “high RI” refer to the relativevalues for the RI of each layer relative to the RI of another layerwithin the anti-reflective coating 120 (e.g., low RI<high RI). In one ormore embodiments, the term “low RI” when used with the first low RIlayer 130A or with the capping layer 131, includes a range from about1.3 to about 1.7. In one or more embodiments, the term “high RI” whenused with the high RI layer 130B, includes a range from about 1.6 toabout 2.5. In some instances, the ranges for low RI and high RI mayoverlap; however, in most instances, the layers of the anti-reflectivecoating 120 have the general relationship regarding RI of: low RI<highRI.

Exemplary materials suitable for use in the anti-reflective coating 120include: SiO₂, Al₂O₃, GeO₂, SiO, AlO_(x)N_(y), AlN, oxygen-dopedSiN_(x), SiN_(x), SiO_(x)N_(y), Si_(u)Al_(v)O_(x)N_(y), TiO₂, ZrO₂, TiN,MgO, HfO₂, Y₂O₃, ZrO₂, diamond-like carbon, and MgAl₂O₄.

Some examples of suitable materials for use in the low RI layer(s) 130Ainclude SiO₂, Al₂O₃, GeO₂, SiO, AlO_(x)N_(y), SiO_(x)N_(y),Si_(u)Al_(v)O_(x)N_(y), MgO, and MgAl₂O₄. The nitrogen content of thematerials for use in the first low RI layer 130A (i.e., the layer 130Ain contact with the substrate 110) may be minimized (e.g., in materials,for example, Al₂O₃ and MgAl₂O₄). In some embodiments, the low RIlayer(s) 130A and a capping layer 131, if present, in theanti-reflective coating 120 can comprise one or more of asilicon-containing oxide (e.g., silicon dioxide), a silicon-containingnitride (e.g., an oxide-doped silicon nitride, silicon nitride, etc.),and a silicon-containing oxynitride (e.g., silicon oxynitride). In someembodiments of the article 100, the low RI layer(s) 130A and the cappinglayer 131 comprise a silicon-containing oxide, e.g., SiO₂.

Some examples of suitable materials for use in the high RI layer(s) 130Binclude Si_(u)Al_(v)O_(x)N_(y), AN, oxygen-doped SiN_(x), SiN_(x),Si₃N₄, AlO_(x)N_(y), SiO_(x)N_(y), HfO₂, TiO₂, ZrO₂, Y₂O₃, ZrO₂, Al₂O₃,and diamond-like carbon. The oxygen content of the materials for thehigh RI layer(s) 130B may be minimized, especially in SiN_(x) or AlN_(x)materials. The foregoing materials may be hydrogenated up to about 30%by weight. In some embodiments, the high RI layer(s) 130B in theanti-reflective coating 120 can comprise one or more of asilicon-containing oxide (e.g., silicon dioxide), a silicon-containingnitride (e.g., an oxide-doped silicon nitride, silicon nitride, etc.),and a silicon-containing oxynitride (e.g., silicon oxynitride). In someembodiments of the article 100, the high RI layer(s) 130B comprise asilicon-containing nitride, e.g., Si₃N₄. Where a material having amedium refractive index is desired between a high RI and a low RI, someembodiments may utilize AlN and/or SiO_(x)N_(y). The hardness of thehigh RI layer may be characterized specifically. In some embodiments,the maximum hardness of the high RI layer(s) 130B, as measured by theBerkovich Indenter Hardness Test over an indentation depth from about100 nm to about 500 nm (i.e., as on a hardness test stack with a 2micron thick layer of the material of the layer 130B disposed on asubstrate 110), may be about 18 GPa or greater, about 20 GPa or greater,about 22 GPa or greater, about 24 GPa or greater, about 26 GPa orgreater, and all values therebetween.

In one or more embodiments at least one of the layers of theanti-reflective coating 120 of the article 100 may include a specificoptical thickness range. As used herein, the term “optical thickness” isdetermined by (n*d), where “n” refers to the RI of the sub-layer and “d”refers to the physical thickness of the layer. In one or moreembodiments, at least one of the layers of the anti-reflective coating120 may include an optical thickness in the range from about 2 nm toabout 200 nm, from about 10 nm to about 100 nm, or from about 15 nm toabout 100 nm. In some embodiments, all of the layers in theanti-reflective coating 120 may each have an optical thickness in therange from about 2 nm to about 200 nm, from about 10 nm to about 100 nm,or from about 15 nm to about 100 nm. In some cases, at least one layerof the anti-reflective coating 120 has an optical thickness of about 50nm or greater. In some cases, each of the low RI layers 130A have anoptical thickness in the range from about 2 nm to about 200 nm, fromabout 10 nm to about 100 nm, or from about 15 nm to about 100 nm. Inother cases, each of the high RI layers 130B have an optical thicknessin the range from about 2 nm to about 200 nm, from about 10 nm to about100 nm, or from about 15 nm to about 100 nm. In some embodiments, eachof the high RI layers 130B have an optical thickness in the range fromabout 2 nm to about 500 nm, or from about 10 nm to about 490 nm, or fromabout 15 nm to about 480 nm, or from about 25 nm to about 475 nm, orfrom about 25 nm to about 470 nm, or from about 30 nm to about 465 nm,or from about 35 nm to about 460 nm, or from about 40 nm to about 455nm, or from about 45 nm to about 450 nm, and any and all sub-rangesbetween these values. In some embodiments, the capping layer 131 (seeFIGS. 2A, 2B and 3), or the outermost low RI layer 130A forconfigurations without a capping layer 131, has a physical thickness ofless than about 100 nm, less than about 90 nm, less than about 85 nm, orless than 80 nm.

As noted earlier, embodiments of the article 100 are configured suchthat the physical thickness of one or more of the layers of theanti-reflective coating 120 are minimized. In one or more embodiments,the physical thickness of the high RI layer(s) 130B and/or the low RIlayer(s) 130A are minimized such that they total less than 500 nm. Inone or more embodiments, the combined physical thickness of the high RIlayer(s) 130B, the low RI layer(s) 130A and any capping layer 131 isless than 500 nm, less than 490 nm, less than 480 nm, less than 475 nm,less than 470 nm, less than 460 nm, less than about 450 nm, less than440 nm, less than 430 nm, less than 425 nm, less than 420 nm, less than410 nm, less than about 400 nm, less than about 350 nm, less than about300 nm, less than about 250 nm, or less than about 200 nm, and all totalthickness values below 500 nm and above 10 nm. For example, the combinedphysical thickness of the high RI layer(s) 130B, the low RI layer(s)130A and any capping layer 131 may be from 10 nm to 490 nm, or from 10nm to 480 nm, or from 10 nm to 475 nm, or from 10 nm to 460 nm, or from10 nm to 450 nm, or from 10 nm to 450 nm, or from 10 nm to 430 nm, orfrom 10 nm to 425 nm, or from 10 nm to 420 nm, or from 10 nm to 410 nm,or from 10 nm to 400 nm, or from 10 nm to 350 nm, or from 10 nm to 300nm, or from 10 nm to 250 nm, or from 10 nm to 225 nm, or from 10 nm to200 nm, or from 15 nm to 490 nm, or from 20 nm to 490 nm, or from 25 nmto 490 nm, or from 30 nm to 490 nm, or from 35 nm to 490 nm, or from 40nm to 490 nm, or from 45 nm to 490 nm, or from 50 nm to 490 nm, or from55 nm to 490 nm, or from 60 nm to 490 nm, or from 65 nm to 490 nm, orfrom 70 nm to 490 nm, or from 75 nm to 490 nm, or from 80 nm to 490 nm,or from 85 nm to 490 nm, or from 90 nm to 490 nm, or from 95 nm to 490nm, or from 100 nm to 490 nm, or from 10 nm to 485 nm, or from 15 nm to480 nm, or from 20 nm to 475 nm, or from 25 nm to 460 nm, or from 30 nmto 450 nm, or from 35 nm to 440 nm, or from 40 nm to 430 nm, or from 50nm to 425 nm, or from 55 nm to 420 nm, or from 60 nm to 410 nm, or from70 nm to 400 nm, or from 75 nm to 400 nm, or from 80 nm to 390 nm, orfrom 90 nm to 380 nm, or from 100 nm to 375 nm, or from 110 nm to 370nm, or from 120 nm to 360 nm, or from 125 nm to 350 nm, or from 130 nmto 325 nm, or from 140 nm to 320 nm, or from 150 nm to 310 nm, or from160 nm to 300 nm, or from 170 nm to 300 nm, or from 175 nm to 300 nm, orfrom 180 nm to 290 nm, or from 190 nm to 280 nm, or from 200 nm to 275nm.

In one or more embodiments, the combined physical thickness of the highRI layer(s) 130B may be characterized. For example, in some embodiments,the combined physical thickness of the high RI layer(s) 130B may beabout 90 nm or greater, about 100 nm or greater, about 150 nm orgreater, about 200 nm or greater, about 250 nm or greater, or about 300nm or greater, but less than 500 nm. The combined physical thickness isthe calculated combination of the physical thicknesses of the individualhigh RI layer(s) 130B in the anti-reflective coating 120, even whenthere are intervening low RI layer(s) 130A or other layer(s). In someembodiments, the combined physical thickness of the high RI layer(s)130B, which may also comprise a high-hardness material (e.g., a nitrideor an oxynitride), may be greater than 30% of the total physicalthickness of the anti-reflective coating (or, alternatively referred toin the context of volume). For example, the combined physical thickness(or volume) of the high RI layer(s) 130B may be about 30% or greater,about 35% or greater, about 40% or greater, about 45% or greater, about50% or greater, about 55% or greater, or even about 60% or greater, ofthe total physical thickness (or volume) of the anti-reflective coating120.

In some embodiments, the anti-reflective coating 120 exhibits a photopicaverage light reflectance of 1% or less, 0.9% or less, 0.8% or less,0.7% or less, 0.6% or less, 0.5% or less, 0.4% or less, 0.3% or less,0.25% or less, or 0.2% or less, over the optical wavelength regime, whenmeasured at the anti-reflective surface 122 (e.g., when removing thereflections from an uncoated back surface (e.g., 114 in FIG. 1) of thearticle 100, for example through using index-matching oils on the backsurface coupled to an absorber, or other known methods). In someinstances, the anti-reflective coating 120 may exhibit such averagelight reflectance over other wavelength ranges, for example, from about450 nm to about 650 nm, from about 420 nm to about 680 nm, from about420 nm to about 700 nm, from about 420 nm to about 740 nm, from about420 nm to about 850 nm, or from about 420 nm to about 950 nm. In someembodiments, the anti-reflective surface 122 exhibits a photopic averagelight transmission of about 90% or greater, 92% or greater, 94% orgreater, 96% or greater, or 98% or greater, over the optical wavelengthregime. In some embodiments, the anti-reflective surface 122 exhibits anaverage light transmission of about 87% or greater, 88% or greater, 89%or greater, 90% or greater, 91% or greater, 92% or greater, 93% orgreater, 94% or greater, or 95% or greater, over the optical wavelengthregime in the infrared spectrum from 800 nm to 1000 nm, from 900 nm to1000 nm, or from 930 nm to 950 nm. Unless otherwise specified, theaverage reflectance or transmittance is measured at an incidentillumination angle of 0 degrees (however, such measurements may beprovided at incident illumination angles of 45 degrees or 60 degrees).

The article 100 may include one or more additional coatings 140 disposedon the anti-reflective coating, as shown in FIG. 3. In one or moreembodiments, the additional coating may include an easy-to-cleancoating. An example of a suitable easy-to-clean coating is described inU.S. patent application Ser. No. 13/690,904, entitled “PROCESS FORMAKING OF GLASS ARTICLES WITH OPTICAL AND EASY-TO-CLEAN COATINGS,” filedon Nov. 30, 2012, which is incorporated herein in its entirety byreference. The easy-to-clean coating may have a physical thickness inthe range from about 5 nm to about 50 nm and may include knownmaterials, for example, fluorinated silanes. In some embodiments, theeasy-to-clean coating may have a physical thickness in the range fromabout 1 nm to about 40 nm, from about 1 nm to about 30 nm, from about 1nm to about 25 nm, from about 1 nm to about 20 nm, from about 1 nm toabout 15 nm, from about 1 nm to about 10 nm, from about 5 nm to about 50nm, from about 10 nm to about 50 nm, from about 15 nm to about 50 nm,from about 7 nm to about 20 nm, from about 7 nm to about 15 nm, fromabout 7 nm to about 12 nm or from about 7 nm to about 10 nm, and allranges and sub-ranges therebetween.

The additional coating 140 may include a scratch resistant coating.Exemplary materials used in the scratch resistant coating may include aninorganic carbide, nitride, oxide, diamond-like material, or combinationof these. Examples of suitable materials for the scratch resistantcoating include metal oxides, metal nitrides, metal oxynitride, metalcarbides, metal oxycarbides, and/or combinations thereof. Exemplarymetals include B, Al, Si, Ti, V, Cr, Y, Zr, Nb, Mo, Sn, Hf, Ta and W.Specific examples of materials that may be utilized in the scratchresistant coating may include Al₂O₃, AlN, AlO_(x)N_(y), Si₃N₄,SiO_(x)N_(y), Si_(u)Al_(v)O_(x)N_(y), diamond, diamond-like carbon,Si_(x)C_(y), Si_(x)O_(y)C_(z), ZrO₂, TiO_(x)N_(y) and combinationsthereof.

In some embodiments, the additional coating 140 includes a combinationof easy-to-clean material and scratch resistant material. In oneexample, the combination includes an easy-to-clean material anddiamond-like carbon. Such additional coatings 140 may have a physicalthickness in the range from about 5 nm to about 20 nm. The constituentsof the additional coating 140 may be provided in separate layers. Forexample, the diamond-like carbon material may be disposed as a firstlayer and the easy-to-clean material can be disposed as a second layeron the first layer of diamond-like carbon. The physical thicknesses ofthe first layer and the second layer may be in the ranges provided abovefor the additional coating. For example, the first layer of diamond-likecarbon may have a physical thickness of about 1 nm to about 20 nm orfrom about 4 nm to about 15 nm (or more specifically about 10 nm) andthe second layer of the easy-to-clean material may have a physicalthickness of about 1 nm to about 10 nm (or more specifically about 6nm). The diamond-like coating may include tetrahedral amorphous carbon(Ta—C), Ta—C:H, and/or Ta—C—H.

A further aspect of this disclosure pertains to a method for forming thearticles 100 described herein (e.g., as shown in FIGS. 1-3). In someembodiments, the method includes providing a substrate having a majorsurface in a coating chamber, forming a vacuum in the coating chamber,forming a durable anti-reflective coating having a physical thickness ofabout 500 nm or less on the major surface, optionally forming anadditional coating comprising at least one of an easy-to-clean coatingand a scratch resistant coating, as situated on the anti-reflectivecoating, and removing the substrate from the coating chamber. In one ormore embodiments, the anti-reflective coating and the additional coatingare formed in either the same coating chamber or without breaking vacuumin separate coating chambers.

In one or more embodiments, the method may include loading the substrateon carriers which are then used to move the substrate in and out ofdifferent coating chambers, under load lock conditions so that a vacuumis preserved as the substrate is moved.

The anti-reflective coating 120 (e.g., including layers 130A, 130B and131) and/or the additional coating 140 may be formed using variousdeposition methods, for example, vacuum deposition techniques, chemicalvapor deposition (e.g., plasma enhanced chemical vapor deposition(PECVD), low-pressure chemical vapor deposition, atmospheric pressurechemical vapor deposition, and plasma-enhanced atmospheric pressurechemical vapor deposition), physical vapor deposition (e.g., reactive ornonreactive sputtering or laser ablation), thermal or e-beam evaporationand/or atomic layer deposition. Liquid-based methods may also be usedfor example spraying or slot coating. Where vacuum deposition isutilized, inline processes may be used to form the anti-reflectivecoating 120 and/or the additional coating 140 in one deposition run. Insome instances, the vacuum deposition can be made by a linear PECVDsource. In some implementations of the method, and articles 100 madeaccording to the method, the anti-reflective coating 120 can be preparedusing a sputtering process (e.g., a reactive sputtering process),chemical vapor deposition (CVD) process, plasma-enhanced chemical vapordeposition process, or some combination of these processes. In oneimplementation, an anti-reflective coating 120 comprising low RIlayer(s) 130A and high RI layer(s) 130B can be prepared according to areactive sputtering process. According to some embodiments, theanti-reflective coating 120 (including low RI layer 130A, high RI layer130B and capping layer 131) of the article 100 is fabricated using ametal-mode, reactive sputtering in a rotary drum coater. The reactivesputtering process conditions were defined through carefulexperimentation to achieve the desired combinations of hardness,refractive index, optical transparency, low color and controlled filmstress.

In some embodiments, the method may include controlling the physicalthickness of the anti-reflective coating 120 (e.g., including its layers130A, 130B and 131) and/or the additional coating 140 so that it doesnot vary by more than about 4% along about 80% or more of the area ofthe anti-reflective surface 122 or from the target physical thicknessfor each layer at any point along the substrate area. In someembodiments, the physical thickness of the anti-reflective layer coating120 and/or the additional coating 140 is controlled so that it does notvary by more than about 4% along about 95% or more of the area of theanti-reflective surface 122.

In some embodiments of the article 100 depicted in FIGS. 1-3, theanti-reflective coating 120 is characterized by a residual stress ofless than about +50 MPa (tensile) to about −1000 MPa (compression). Insome implementations of the article 100, the anti-reflective coating 120is characterized by a residual stress from about −50 MPa to about −1000MPa (compression), or from about −75 MPa to about −800 MPa(compression). Unless otherwise noted, residual stress in theanti-reflective coating 120 is obtained by measuring the curvature ofthe substrate 110 before and after deposition of the anti-reflectivecoating 120, and then calculating residual film stress according to theStoney equation according to principles known and understood by thosewith ordinary skill in the field of the disclosure.

The articles 100 disclosed herein (e.g., as shown in FIGS. 1-3) may beincorporated into a device article, for example, a device article with adisplay (or display device articles) (e.g., consumer electronics,including mobile phones, tablets, computers, navigation systems,wearable devices (e.g., watches) and the like), augmented-realitydisplays, heads-up displays, glasses-based displays, architecturaldevice articles, transportation device articles (e.g., automotive,trains, aircraft, sea craft, etc.), appliance device articles, or anydevice article that benefits from some transparency, scratch-resistance,abrasion resistance or a combination thereof. An exemplary devicearticle incorporating any of the articles disclosed herein (e.g., asconsistent with the articles 100 depicted in FIGS. 1-3) is shown inFIGS. 4A and 4B. Specifically, FIGS. 4A and 4B show a consumerelectronic device 400 including a housing 402 having a front 404, a back406, and side surfaces 408; electrical components (not shown) that areat least partially inside or entirely within the housing and includingat least a controller, a memory, and a display 410 at or adjacent to thefront surface of the housing; and a cover substrate 412 at or over thefront surface of the housing such that it is over the display. In someembodiments, the cover substrate 412 may include any of the articlesdisclosed herein. In some embodiments, at least one of a portion of thehousing or the cover glass comprises the articles disclosed herein.

According to some embodiments, the articles 100 (e.g., as shown in FIGS.1-3) may be incorporated within a vehicle interior with vehicularinterior systems, as depicted in FIG. 5. More particularly, the article100 may be used in conjunction with a variety of vehicle interiorsystems. A vehicle interior 540 is depicted that includes threedifferent examples of a vehicle interior system 544, 548, 552. Vehicleinterior system 544 includes a center console base 556 with a surface560 including a display 564. Vehicle interior system 548 includes adashboard base 568 with a surface 572 including a display 576. Thedashboard base 568 typically includes an instrument panel 580 which mayalso include a display. Vehicle interior system 552 includes a dashboardsteering wheel base 584 with a surface 588 and a display 592. In one ormore examples, the vehicle interior system may include a base that is anarmrest, a pillar, a seat back, a floor board, a headrest, a door panel,or any portion of the interior of a vehicle that includes a surface. Itwill be understood that the article 100 described herein can be usedinterchangeably in each of vehicle interior systems 544, 548 and 552.

According to some embodiments, the articles 100 (e.g., as shown in FIGS.1-3) may be used in a passive optical element, for example a lens,windows, lighting covers, eyeglasses, or sunglasses, that may or may notbe integrated with an electronic display or electrically active device.

Referring again to FIG. 5, the displays 564, 576 and 592 may eachinclude a housing having front, back, and side surfaces. At least oneelectrical component is at least partially within the housing. A displayelement is at or adjacent to the front surface of the housings. Thearticle 100 (see FIGS. 1-3) is disposed over the display elements. Itwill be understood that the article 100 may also be used on, or inconjunction with, the armrest, the pillar, the seat back, the floorboard, the headrest, the door panel, or any portion of the interior of avehicle that includes a surface, as explained above. According tovarious examples, the displays 564, 576 and 592 may be a vehicle visualdisplay system or vehicle infotainment system. It will be understoodthat the article 100 may be incorporated in a variety of displays andstructural components of autonomous vehicles and that the descriptionprovided herein with relation to conventional vehicles is not limiting.

EXAMPLES

Various embodiments will be further clarified by the following examples.

Example 1

The as-fabricated samples of Example 1 (“Ex. 1”) were formed byproviding a glass substrate having a nominal composition of 69 mol. %SiO₂, 10 mol. % Al₂O₃, 15 mol. % Na₂O, and 5 mol. % MgO and disposing ananti-reflective coating having five (5) layers on the glass substrate,as shown in FIG. 2B and Table 1 below. The anti-reflective coating(e.g., as consistent with the anti-reflective coatings 120 outlined inthe disclosure) of each of the as-fabricated samples in this Example wasdeposited using a reactive sputtering process.

The modeled samples of Example 1 (“Ex. 1-M”) were assumed to employ aglass substrate having the same composition of the glass substrateemployed in the as-fabricated samples of this example. Further, theanti-reflective coating of each of the modeled samples was assumed tohave the layer materials and physical thickness as shown in Table 1below. Optical properties reported for all examples were measured atnear-normal incidence, unless otherwise noted.

TABLE 1 Anti-reflective coating attributes for Example 1 Reference No.Refractive Ex. 1-M Ex. 1 (see FIG. 2B) Material Index Thickness (nm) N/AAir 1.0 131 SiO₂ 1.48 84.7 86.0 130B Si_(x)N_(y) 2.05 96.1 97.9 130ASiO₂ 1.48 21.2 21.7 130B Si_(x)N_(y) 2.05 20.3 20.1 130A SiO₂ 1.48 25.025.0 110 Glass substrate 1.51 Total thickness 247.3 250.7 Reflectedcolor Y 0.35 0.28 L* 3.2 5.8 a* −1.2 0.9 b* −2.7 −5.7 Hardness (GPa) @100 nm depth 10.6 @ 500 nm depth 8.8 Max hardness Hmax (GPa) 11.4 (from100 nm to Depth (nm) 147.0 500 nm depth) Film stress (MPa) −466 Surface(nm) 0.83 roughness, R_(a)

Example 2

The as-fabricated samples of Example 2 (“Ex. 2”) were formed byproviding a glass substrate having a nominal composition of 69 mol. %SiO₂, 10 mol. % Al₂O₃, 15 mol. % Na₂O, and 5 mol. % MgO and disposing ananti-reflective coating having five (5) layers on the glass substrate,as shown in FIG. 2B and Table 2 below. The anti-reflective coating(e.g., as consistent with the anti-reflective coatings 120 outlined inthe disclosure) of each of the as-fabricated samples in this Example wasdeposited using a reactive sputtering process.

The modeled samples of Example 2 (“Ex. 2-M”) were assumed to employ aglass substrate having the same composition of the glass substrateemployed in the as-fabricated samples of this example. Further, theanti-reflective coating of each of the modeled samples was assumed tohave the layer materials and physical thickness as shown in Table 2below.

TABLE 2 Anti-reflective coating attributes for Example 2 Reference No.Refractive Ex. 2-M Ex. 2 (see FIG. 2B) Material Index Thickness (nm) N/AAir 1.0 131 SiO₂ 1.48 81.7 81.1 130B Si_(x)N_(y) 2.05 119.0 117.8 130ASiO₂ 1.48 33.3 32.7 130B Si_(x)N_(y) 2.05 14.2 14.4 130A SiO₂ 1.48 25.025.0 110 Glass substrate 1.51 Total thickness 273.2 271.0 Reflectedcolor Y 0.56 0.47 L* 5.1 6.4 a* −1.5 −0.3 b* −3.4 −3.7 Hardness (GPa) @100 nm depth 11.1 @ 500 nm depth 8.9 Max hardness Hmax (GPa) 11.8 (from100 nm to Depth (nm) 135.0 500 nm depth) Film stress (MPa) −521 Surface(nm) 0.91 roughness, R_(a)

Example 3

The as-fabricated samples of Example 3 (“Ex. 3”) were formed byproviding a glass substrate having a nominal composition of 69 mol. %SiO₂, 10 mol. % Al₂O₃, 15 mol. % Na₂O, and 5 mol. % MgO and disposing ananti-reflective coating having five (5) layers on the glass substrate,as shown in FIG. 2B and Table 3 below. The anti-reflective coating(e.g., as consistent with the anti-reflective coatings 120 outlined inthe disclosure) of each of the as-fabricated samples in this Example wasdeposited using a reactive sputtering process.

The modeled samples of Example 3 (“Ex. 3-M”) were assumed to employ aglass substrate having the same composition of the glass substrateemployed in the as-fabricated samples of this example. Further, theanti-reflective coating of each of the modeled samples was assumed tohave the layer materials and physical thickness as shown in Table 3below.

TABLE 3 Anti-reflective coating attributes for Example 3 Reference No.Refractive Ex. 3-M Ex. 3 (see FIG. 2B) Material Index Thickness (nm) N/AAir 1.0 131 SiO₂ 1.48 90.7 89.7 130B Si_(x)N_(y) 2.05 70.0 69.9 130ASiO₂ 1.48 23.3 21.5 130B Si_(x)N_(y) 2.05 27.5 27.5 130A SiO₂ 1.48 25.025.0 110 Glass substrate 1.51 Total thickness 236.5 233.6 Reflectedcolor Y 0.28 0.24 L* 2.5 2.9 a* 0.1 −0.9 b* −3.1 −1.3 Hardness (GPa) @100 nm depth 10.5 @ 500 nm depth 8.9 Max hardness Hmax (GPa) 10.7 (from100 nm to Depth (nm) 135.0 500 nm depth) Film stress (MPa) −523 Surface(nm) 0.83 roughness, R_(a)

Example 3A

The as-fabricated samples of Example 3A (“Ex. 3A”) were formed byproviding a glass substrate having a nominal composition of 69 mol. %SiO₂, 10 mol. % Al₂O₃, 15 mol. % Na₂O, and 5 mol. % MgO and disposing ananti-reflective coating having five (5) layers on the glass substrate,as shown in FIG. 2B and Table 3A below. The anti-reflective coating(e.g., as consistent with the anti-reflective coatings 120 outlined inthe disclosure) of each of the as-fabricated samples in this Example wasdeposited using a reactive sputtering process.

The modeled samples of Example 3A (“Ex. 3-M”) were assumed to employ aglass substrate having the same composition of the glass substrateemployed in the as-fabricated samples of this example. Further, theanti-reflective coating of each of the modeled samples was assumed tohave the layer materials and physical thickness as shown in Table 3Abelow.

TABLE 3A Anti-reflective coating attributes for Example 3A Reference No.Refractive Ex. 3-M Ex. 3A (see FIG. 2B) Material Index Thickness (nm)N/A Air 1.0 131 SiO₂ 1.48 90.7 90.8 130B Si_(x)N_(y) 2.05 70.0 73.5 130ASiO₂ 1.48 23.3 20.6 130B Si_(x)N_(y) 2.05 27.5 27.4 130A SiO₂ 1.48 25.025.0 110 Glass substrate 1.51 Total thickness 236.5 237.4 Reflectedcolor Y 0.28 0.24 L* 2.5 4.3 a* 0.1 0.7 b* −3.1 −3.7 Hardness (GPa) @100 nm depth 10.2 @ 500 nm depth 8.8 Max hardness Hmax (GPa) 10.5 (from100 nm to Depth (nm) 135.0 500 nm depth) Film stress (MPa) −517 Surface(nm) 0.85 roughness, R_(a)

Example 4

The as-fabricated samples of Example 4 (“Ex. 4”) were formed byproviding a glass substrate having a nominal composition of 69 mol. %SiO₂, 10 mol. % Al₂O₃, 15 mol. % Na₂O, and 5 mol. % MgO and disposing ananti-reflective coating having seven (7) layers on the glass substrate,as shown in FIG. 2A and Table 4 below. The anti-reflective coating(e.g., as consistent with the anti-reflective coatings 120 outlined inthe disclosure) of each of the as-fabricated samples in this Example wasdeposited using a reactive sputtering process.

The modeled samples of Example 4 (“Ex. 4-M”) were assumed to employ aglass substrate having the same composition of the glass substrateemployed in the as-fabricated samples of this example. Further, theanti-reflective coating of each of the modeled samples was assumed tohave the layer materials and physical thickness as shown in Table 4below.

TABLE 4 Anti-reflective coating attributes for Example 4 Reference No.Refractive Ex. 4-M Ex. 4 (see FIG. 2A) Material Index Thickness (nm) N/AAir 1.0 131 SiO₂ 1.48 87.0 89.5 130B Si_(x)N_(y) 2.05 135.1 136.1 130ASiO₂ 1.48 9.3 9.2 130B Si_(x)N_(y) 2.05 135.7 138.3 130A SiO₂ 1.48 28.028.1 130B Si_(x)N_(y) 2.05 19.7 19.9 130A SiO₂ 1.48 25.0 25.0 110 Glasssubstrate 1.51 Total thickness 439.7 446.1 Reflected color Y 0.41 0.39L* 3.7 6.5 a* −0.8 −3.0 b* −4.0 −5.1 Hardness (GPa) @ 100 nm depth 11.3@ 500 nm depth 10.3 Max hardness Hmax (GPa) 13.5 (from 100 nm to Depth(nm) 172.0 500 nm depth) Film stress (MPa) −724 Surface (nm) 1.00roughness, R_(a)

Example 5

The as-fabricated samples of Example 5 (“Ex. 5”) were formed byproviding a glass substrate having a nominal composition of 69 mol. %SiO₂, 10 mol. % Al₂O₃, 15 mol. % Na₂O, and 5 mol. % MgO and disposing ananti-reflective coating having five (5) layers on the glass substrate,as shown in FIG. 2B and Table 5 below. The anti-reflective coating(e.g., as consistent with the anti-reflective coatings 120 outlined inthe disclosure) of each of the as-fabricated samples in this Example wasdeposited using a reactive sputtering process.

The modeled samples of Example 5 (“Ex. 5-M”) were assumed to employ aglass substrate having the same composition of the glass substrateemployed in the as-fabricated samples of this example. Further, theanti-reflective coating of each of the modeled samples was assumed tohave the layer materials and physical thickness as shown in Table 5Abelow.

TABLE 5A Anti-reflective coating attributes for Example 5 Reference No.Refractive Ex. 5-M Ex. 5 (see FIG. 2B) Material Index Thickness (nm) N/AAir 1.0 131 SiO₂ 1.48 82.2 81.9 130B Si_(x)N_(y) 2.05 225.0 226.6 130ASiO₂ 1.48 15.7 16.7 130B Si_(x)N_(y) 2.05 28.2 27.9 130A SiO₂ 1.48 25.025.0 110 Glass substrate 1.51 Total thickness 376.0 378.0 Reflectedcolor Y 0.80 0.77 L* 7.2 10.2 a* −2.0 −1.2 b* −4.4 −5.5 Hardness (GPa) @100 nm depth 11.9 @ 500 nm depth 9.7 Max hardness Hmax (GPa) 13.7 (from100 nm to Depth (nm) 200.0 500 nm depth) Film stress (MPa) −770 Surface(nm) 0.99 roughness, R_(a)

Example 5A

The as-fabricated samples of Example 5A (“Ex. 5A”) were formed byproviding a glass substrate having a nominal composition of 69 mol. %SiO₂, 10 mol. % Al₂O₃, 15 mol. % Na₂O, and 5 mol. % MgO and disposing ananti-reflective coating having five (5) layers on the glass substrate,as shown in FIG. 2B and Table 5B below. The anti-reflective coating(e.g., as consistent with the anti-reflective coatings 120 outlined inthe disclosure) of each of the as-fabricated samples in this Example wasdeposited using a reactive sputtering process.

The modeled samples of Example 5A (“Ex. 5-M”) were assumed to employ aglass substrate having the same composition of the glass substrateemployed in the as-fabricated samples of this example. Further, theanti-reflective coating of each of the modeled samples was assumed tohave the layer materials and physical thickness as shown in Table 5Bbelow.

TABLE 5B Anti-reflective coating attributes for Example 5A Reference No.Refractive Ex. 5-M Ex. 5A (see FIG. 2B) Material Index Thickness (nm)N/A Air 1.0 131 SiO₂ 1.48 82.2 85.1 130B Si_(x)N_(y) 2.05 225.0 220.9130A SiO₂ 1.48 15.7 19.6 130B Si_(x)N_(y) 2.05 28.2 27.8 130A SiO₂ 1.4825.0 25.0 110 Glass substrate 1.51 Total thickness 376.0 378.5 Reflectedcolor Y 0.80 0.88 L* 7.2 9.4 a* −2.0 −3.5 b* −4.4 −2.5 Hardness (GPa) @100 nm depth 10.9 @ 500 nm depth 9.7 Max hardness Hmax (GPa) 12.8 (from100 nm to Depth (nm) 172.0 500 nm depth) Film stress (MPa) −78 Surface(nm) 1.03 roughness, R_(a)

Referring now to FIG. 6, a plot of hardness vs. indentation depth forthe as-fabricated articles of Examples 1, 2, 3, 4, 5 and 5A is provided.The data shown in FIG. 6 was generated by employing a Berkovich IndenterHardness Test on the samples of Examples 1-5A. As is evident from FIG.6, hardness values peak at an indentation depth from 150 to 250 nm.Further, the as-fabricated samples of Examples 4, 5 and 5A exhibited thehighest hardness values at indentation depths of 100 nm and 500 nm, andthe highest maximum hardness values within the indentation depth from100 nm to 500 nm.

Referring now to FIG. 7, a plot is provided of first-surface, reflectedcolor coordinates measured at, or estimated for, near-normal incidenceof the samples outlined above in Examples 1-5A. As is evident from FIG.7, there is a fairly good correlation between the color coordinatesexhibited by the as-fabricated and modeled samples from each of theExamples. Further, the color coordinates exhibited by the samples shownin FIG. 7 are indicative of limited color shifting associated with theanti-reflective coatings of the disclosure.

Example 6

Example 6 is directed to two sets of modeled samples. In particular, themodeled samples of Example 6 (“Ex. 3-M” and “Ex. 6-M”) were assumed toemploy a glass substrate having the same composition of the glasssubstrate employed in the as-fabricated samples of this example. Notethat the Ex. 3-M modeled sample in Example 6 employs the sameconfiguration of the anti-reflective coating as employed in Example 3,i.e., Ex. 3-M. The Ex. 6-M sample, however, has a similaranti-reflective coating configuration, but with a thicker low RI layerin contact with the substrate. More particularly, the anti-reflectivecoating of each of the modeled samples was assumed to have the layermaterials and physical thickness as shown in Table 6 below. As isevident from the data shown in Table 6, the Ex. 6-M sample exhibits aneven lower photopic average reflectance (i.e., Y value) as compared tothe modeled sample, Ex. 3-M.

TABLE 6 Anti-reflective coating attributes for Example 6 Reference No.Refractive Ex. 3-M Ex. 6-M (see FIG. 2B) Material Index Thickness (nm)N/A Air 1.0 131 SiO₂ 1.48 90.7 89.3 130B Si_(x)N_(y) 2.05 70.0 70.0 130ASiO₂ 1.48 23.3 26.3 130B Si_(x)N_(y) 2..05 27.5 23.5 130A SiO₂ 1.48 25.053.6 110 Glass substrate 1.51 Total thickness 236.5 262.62 Reflectedcolor Y 0.28 0.196 L* 2.5 1.8 a* 0.1 4.3 b* −3.1 −5.2

Referring now to FIG. 8, a plot of specular component excluded (SCE)values is provided for samples of the prior Examples, specifically, Exs.1-5, as obtained from samples subjected to the Alumina SCE Test.Further, SCE values are also reported from a comparative article (“Comp.Ex. 1”), which includes the same substrate as employed in Exs. 1-5 andhas a conventional anti-reflective coating comprising niobia and silica.Notably, the samples from Examples 1-5 of the disclosure (i.e., Exs.1-5) exhibited SCE values of about 0.2% or less, three times (or more)lower than the SCE value reported for the comparative sample (Comp. Ex.1). As noted earlier, lower SCE values are indicative of less severeabrasion-related damage.

Referring now to FIG. 9, a plot is provided of hardness (GPa) vs.indentation depth (nm) for a hardness test stack of high refractiveindex layer material (i.e., a material suitable for a high RI indexlayer 130B as shown in FIGS. 2A and 2B) comprising SiN_(x), consistentwith a high RI layer 130B, according to the disclosure. Notably, theplot in FIG. 9 was obtained by employing the Berkovich Indenter HardnessTest on a test stack comprising a substrate consistent with those inExamples 1-5A and a high index RI layer comprising SiN_(x) having athickness of about 2 microns, to minimize the influence of the substrateand the other test-related articles described earlier in the disclosure.Accordingly, the hardness values observed in FIG. 9 on the 2micron-thick sample are indicative of the actual intrinsic materialhardness of the much thinner, high RI layers employed in theanti-reflective coatings 120 of the disclosure.

Example 7

The as-fabricated samples of Example 7 (“Exs. 7, 7A, 7B and 7C”) wereformed by providing a glass substrate having a nominal composition of 69mol % SiO₂, 10 mol % Al₂O₃, 15 mol % Na₂O, and 5 mol % MgO and disposingan anti-reflective coating having five (5) layers (Exs. 7, 7A and 7B)and seven (7) layers (Ex. 7C) on the glass substrate, as shown in FIGS.2A and 2B and Table 7 below. The anti-reflective coating (e.g., asconsistent with the anti-reflective coatings 120 outlined in thedisclosure) of each of the as-fabricated samples in this Example wasdeposited using a reactive sputtering process. Selected optical andmechanical properties of the samples in this example are also providedbelow in Table 7.

TABLE 7 Anti-reflective coating attributes for Example 7 Reference No.(see FIGS. 2A Refractive Ex. 7 Ex. 7A Ex. 7B Ex. 7C and 2B) MaterialIndex Thickness (nm) N/A Air 1.0 131 SiO₂ 1.47 81.12 85.01 85.89 85.46130B Si_(x)N_(y) 2.01 105.00 105.00 105.00 105.00 130A SiO₂ 1.41 ** **** 18.67 130B Si_(x)N_(y) 1.97 ** ** ** 33.04 130A SiO₂ 1.41 22.31 19.2218.34 53.78 130B Si_(x)N_(y) 1.97 21.38 25.63 26.42 14.58 130A SiO₂ 1.4125.00 25.00 25.00 25.00 110 Glass 1.51 substrate Total thickness 254.8259.9 260.7 335.5 Reflected color Y/R 0.37 0.46 0.50 0.35 (1-sided) a*−0.01 0.37 0.44 −0.20 b* −2.57 −3.21 −3.39 −2.42 Transmittance T % (avg.450 to 650 nm) 97.57 97.49 97.45 97.13 (1-sided) T % (avg. 930 to 950nm) 88.22 89.46 89.70 90.50 Hardness (GPa) @ 100 nm depth 10.9 10.9 10.611.1 @ 500 nm depth 9.0 9.2 9.0 9.2 Max hardness Hmax (GPa) 11.7 11.611.6 12 (from 100 nm to 500 nm depth) Film stress (MPa) −762 −787 −802−690

Referring now to FIG. 10, a plot is provided of first-surface, reflectedtransmittance (%) vs. wavelength (i.e., from 350 nm to 950 nm) measuredat, or estimated for, near-normal incidence of the samples outlinedabove in Example 7 (Exs. 7, 7A, 7B and 7C). As is evident from FIG. 10,each of the samples in this example demonstrates an averagetransmittance of greater than 96% in the visible spectrum from 450 nm to650 nm and an average transmittance of greater than or equal to 87% inthe infrared spectrum from 800 nm to 950 nm, from 800 nm to 950 nm, andfrom 930 nm to 950 nm.

As used herein, the “AlO_(x)N_(y),” “SiO_(x)N_(y),” and“Si_(u)Al_(x)O_(y)N_(z)” materials in the disclosure include variousaluminum oxynitride, silicon oxynitride and silicon aluminum oxynitridematerials, as understood by those with ordinary skill in the field ofthe disclosure, described according to certain numerical values andranges for the subscripts, “u,” “x,” “y,” and “z”. That is, it is commonto describe solids with “whole number formula” descriptions, for exampleAl₂O₃. It is also common to describe solids using an equivalent “atomicfraction formula” description for example Al_(0.4)O_(0.6), which isequivalent to Al₂O₃. In the atomic fraction formula, the sum of allatoms in the formula is 0.4+0.6=1, and the atomic fractions of Al and Oin the formula are 0.4 and 0.6, respectively. Atomic fractiondescriptions are described in many general textbooks and atomic fractiondescriptions are often used to describe alloys. See, for example: (i)Charles Kittel, Introduction to Solid State Physics, seventh edition,John Wiley & Sons, Inc., NY, 1996, pp. 611-627; (ii) Smart and Moore,Solid State Chemistry, An introduction, Chapman & Hall University andProfessional Division, London, 1992, pp. 136-151; and (iii) James F.Shackelford, Introduction to Materials Science for Engineers, SixthEdition, Pearson Prentice Hall, New Jersey, 2005, pp. 404-418.

Again referring to the “AlO_(x)N_(y),” “SiO_(x)N_(y),” and“Si_(u)Al_(x)O_(y)N_(z)” materials in the disclosure, the subscriptsallow those with ordinary skill in the art to reference these materialsas a class of materials without specifying particular subscript values.To speak generally about an alloy, for example aluminum oxide, withoutspecifying the particular subscript values, we can speak of Al_(v)O_(x).The description Al_(v)Ox can represent either Al₂O₃ or Al_(0.4)O_(0.6).If v+x were chosen to sum to 1 (i.e., v+x=1), then the formula would bean atomic fraction description. Similarly, more complicated mixtures canbe described, for example Si_(u)Al_(v)O_(x)N_(y), where again, if thesum u+v+x+y were equal to 1, we would have the atomic fractionsdescription case.

Once again referring to the “AlO_(x)N_(y),” “SiO_(x)N_(y),” and“Si_(u)Al_(x)O_(y)N_(z)” materials in the disclosure, these notationsallow those with ordinary skill in the art to readily make comparisonsto these materials and others. That is, atomic fraction formulas aresometimes easier to use in comparisons. For instance, an example alloyconsisting of (Al₂O₃)_(0.3)(AlN)_(0.7) is closely equivalent to theformula descriptions Al_(0.448)O_(0.31)N_(0.241) and also Al₃₆₇O₂₅₄N₁₉₈.Another example alloy consisting of (Al₂O₃)_(0.4)(AlN)_(0.6) is closelyequivalent to the formula descriptions Al_(0.438)O_(0.375)N_(0.188) andAl₃₇O₃₂N₁₆. The atomic fraction formulas Al_(0.448)O_(0.31)N_(0.241) andAl_(0.438)O_(0.375)N_(0.188) are relatively easy to compare to oneanother. For instance, Al decreased in atomic fraction by 0.01, Oincreased in atomic fraction by 0.065 and N decreased in atomic fractionby 0.053. It takes more detailed calculation and consideration tocompare the whole number formula descriptions Al₃₆₇O₂₅₄N₁₉₈ andAl₃₇O₃₂N₁₆. Therefore, it is sometimes preferable to use atomic fractionformula descriptions of solids. Nonetheless, the use of Al_(v)O_(x)N_(y)is general since it captures any alloy containing Al, 0 and N atoms.

As understood by those with ordinary skill in the field of thedisclosure with regard to any of the foregoing materials (e.g., AlN) forthe optical film 80, each of the subscripts, “u,” “x,” “y,” and “z,” canvary from 0 to 1, the sum of the subscripts will be less than or equalto one, and the balance of the composition is the first element in thematerial (e.g., Si or Al). In addition, those with ordinary skill in thefield can recognize that “Si_(u)Al_(x)O_(y)N_(z)” can be configured suchthat “u” equals zero and the material can be described as“AlO_(x)N_(y)”. Still further, the foregoing compositions for theoptical film 80 exclude a combination of subscripts that would result ina pure elemental form (e.g., pure silicon, pure aluminum metal, oxygengas, etc.). Finally, those with ordinary skill in the art will alsorecognize that the foregoing compositions may include other elements notexpressly denoted (e.g., hydrogen), which can result innon-stoichiometric compositions (e.g., SiN_(x) vs. Si₃N₄). Accordingly,the foregoing materials for the optical film can be indicative of theavailable space within a SiO₂—Al₂O₃—SiN_(x)—AlN or aSiO₂—Al₂O₃—Si₃N₄—AlN phase diagram, depending on the values of thesubscripts in the foregoing composition representations.

Many variations and modifications may be made to the above-describedembodiments of the disclosure without departing substantially from thespirit and various principles of the disclosure. All such modificationsand variations are intended to be included herein within the scope ofthis disclosure and protected by the following claims. For example, thevarious features of the disclosure may be combined according to thefollowing embodiments.

Embodiment 1. An article comprising:

an inorganic oxide substrate comprising opposing major surfaces; and

an optical film structure disposed on a first major surface of theinorganic oxide substrate, the optical film structure comprising aphysical thickness from about 50 nm to less than 500 nm and one or moreof a silicon-containing oxide, a silicon-containing nitride, and asilicon-containing oxynitride, the optical film structure,

wherein the article exhibits a hardness of 8 GPa or greater measured atan indentation depth of about 100 nm or a maximum hardness of 9 GPa orgreater measured over an indentation depth range from about 100 nm toabout 500 nm, the hardness and the maximum hardness measured by aBerkovich Indenter Hardness Test, and

further wherein the article exhibits a single-side photopic averagereflectance that is less than 1%.

Embodiment 2. The article of Embodiment 1, wherein the article exhibitsa hardness of 10 GPa or greater measured at an indentation depth ofabout 100 nm or a maximum hardness of 11 GPa or greater measured over anindentation depth range from about 100 nm to about 500 nm, the hardnessand the maximum hardness measured by a Berkovich Indenter Hardness Test,wherein the physical thickness of the optical film structure is fromabout 200 nm to about 450 nm, and further wherein the article exhibits asingle-side photopic average reflectance that is less than 0.6%.

Embodiment 3. The article of Embodiment 1 or Embodiment 2, wherein thearticle exhibits an a* value, in reflectance, from about −10 to +5 and ab* value, in reflectance, from −10 to +2, the a* and b* values eachmeasured on the optical film structure at a near-normal incidentillumination angle.

Embodiment 4. The article of Embodiment 1 or Embodiment 2, wherein thearticle exhibits an a* value, in reflectance, from about −4 to +4 and ab* value, in reflectance, from −6 to −1, the a* and b* values eachmeasured on the optical film structure at a near-normal incidentillumination angle.

Embodiment 5. The article of any one of Embodiments 1-4, wherein thearticle exhibits a maximum hardness of about 12 GPa or greater asmeasured by a Berkovich Indenter Hardness Test over an indentation depthrange from about 100 nm to about 500 nm.

Embodiment 6. The article of any one of Embodiments 1-5, wherein theoptical film structure comprises a residual stress in the range fromabout −1000 MPa (compressive) to about +50 MPa (tensile).

Embodiment 7. The article of any one of Embodiments 1-6, wherein theoptical film structure comprises a silicon-containing oxide and asilicon-containing nitride, and further wherein the silicon-containingoxide is silicon oxide and the silicon-containing nitride is siliconnitride.

Embodiment 8. The article of any one of Embodiments 1-7, wherein theinorganic oxide substrate comprises a glass selected from the groupconsisting of soda lime glass, alkali aluminosilicate glass,alkali-containing borosilicate glass, and alkali aluminoborosilicateglass.

Embodiment 9. The article of Embodiment 8, wherein the glass ischemically strengthened and comprises a compressive stress (CS) layerwith a peak CS of 250 MPa or more, the CS layer extending within thechemically strengthened glass from the first major surface to a depth ofcompression (DOC) of about 10 microns or more.

Embodiment 10. The article of any one of Embodiments 1-9, furthercomprising any one or more of an easy-to-clean coating, a diamond-likecoating, and a scratch resistant coating, disposed on the optical filmstructure.

Embodiment 11. The article of any one of Embodiments 1-10, wherein thearticle exhibits a specular component excluded (SCE) value of 0.2% orless, as measured according to an Alumina SCE Test.

Embodiment 12. An article comprising:

an inorganic oxide substrate comprising opposing major surfaces; and

an optical film structure disposed on a first major surface of theinorganic oxide substrate, the optical film structure comprising aphysical thickness from about 50 nm to less than 500 nm and a pluralityof alternating high index and low index layers with a first low indexlayer on the first major surface and a capping low index layer,

wherein each layer comprises one or more of a silicon-containing oxide,a silicon-containing nitride, and a silicon-containing oxynitride,

wherein a refractive index of the low index layers is within a range ofa refractive index of the substrate such that the refractive index ofthe low index layers is less than about 1.8, and wherein the high indexlayer comprises a refractive index that is greater than 1.8,

wherein the high index layer exhibits a maximum hardness of 18 GPa orgreater as measured by a Berkovich Indenter Hardness Test over anindentation depth from about 100 nm to about 500 nm on a hardness teststack comprising the high index layer with a physical thickness of about2 microns disposed on the inorganic oxide substrate, and

further wherein the article exhibits a single-side photopic averagereflectance that is less than 1%.

Embodiment 13. The article of Embodiment 12, wherein the maximumhardness exhibited by the high index layer is 22 GPa or greater asmeasured by the Berkovich Indenter Hardness Test over an indentationdepth from about 100 nm to about 500 nm on the hardness test stackcomprising the high index layer with the physical thickness of about 2microns disposed on the inorganic substrate, and wherein the physicalthickness of the optical film structure is from about 200 nm to about450 nm, and further wherein the article exhibits a single-side photopicaverage reflectance that is less than 0.6%.

Embodiment 14. The article of Embodiment 12 or Embodiment 13, whereinthe article exhibits an a* value, in reflectance, from about −10 to +5and a b* value, in reflectance, from −10 to +2, the a* and b* valueseach measured on the optical film structure at a near-normal incidentillumination angle.

Embodiment 15. The article of Embodiment 12 or Embodiment 13, whereinthe article exhibits an a* value, in reflectance, from about −4 to +4and a b* value, in reflectance, from −6 to −1, the a* and b* values eachmeasured on the optical film structure at a near-normal incidentillumination angle.

Embodiment 16. The article of any one of Embodiments 12-15, wherein theoptical film structure comprises a residual stress in the range fromabout −1000 MPa (compressive) to about +50 MPa (tensile).

Embodiment 17. The article of any one of Embodiments 12-16, wherein theinorganic oxide substrate comprises a glass selected from the groupconsisting of soda lime glass, alkali aluminosilicate glass,alkali-containing borosilicate glass and alkali aluminoborosilicateglass.

Embodiment 18. The article of Embodiment 17, wherein the glass ischemically strengthened and comprises a compressive stress (CS) layerwith a peak CS of 250 MPa or more, the CS layer extending within thechemically strengthened glass from the first major surface to a depth ofcompression (DOC) of about 10 microns or more.

Embodiment 19. The article of any one of Embodiments 12-18, furthercomprising any one or more of an easy-to-clean coating, a diamond-likecoating, and a scratch resistant coating, disposed on the optical filmstructure.

Embodiment 20. The article of any one of Embodiments 12-19, wherein theplurality of alternating high index and low index layers is at leastfour (4) layers, wherein each layer comprises one or more of asilicon-containing oxide and a silicon-containing nitride, and furtherwherein the silicon-containing oxide is silicon oxide and thesilicon-containing nitride is silicon nitride.

Embodiment 21. The article of any one of Embodiments 12-20, wherein thephysical thickness of the high index layer adjacent to the capping lowindex layer is about 70 nm or more, and the physical thickness of thecapping low index layer is about 80 nm or more.

Embodiment 22. The article of any one of Embodiments 12-21, wherein thearticle exhibits a specular component excluded (SCE) value of 0.2% orless, as measured according to an Alumina SCE Test.

Embodiment 23. An article comprising:

an inorganic oxide substrate comprising opposing major surfaces; and

an optical film structure disposed on a first major surface of theinorganic oxide substrate, the optical film structure comprising aphysical thickness from about 50 nm to less than 500 nm and a pluralityof alternating high index and low index layers with a first low indexlayer on the first major surface of the substrate and a capping lowindex layer,

wherein each layer comprises one or more of a silicon-containing oxide,a silicon-containing nitride, and a silicon-containing oxynitride,

wherein a refractive index of the low index layers is in a range of arefractive index of the inorganic oxide substrate such that therefractive index of the low index layers is less than about 1.8, andwherein the high index layer comprises a refractive index that isgreater than 1.8,

wherein the optical film structure further comprises 30% or more of thehigh index layer by volume, and

further wherein the article exhibits a single-side photopic averagereflectance that is less than 1%.

Embodiment 24. The article of Embodiment 23, wherein the optical filmstructure further comprises 50% or more of the high index layer byvolume.

Embodiment 25. The article of Embodiment 23 or Embodiment 24, whereinthe article exhibits an a* value, in reflectance, from about −10 to +5and a b* value, in reflectance, from −10 to +2, the a* and b* valueseach measured on the optical film structure at a near-normal incidentillumination angle.

Embodiment 26. The article of Embodiment 23 or Embodiment 24, whereinthe article exhibits an a* value, in reflectance, from about −4 to +4and a b* value, in reflectance, from −6 to −1, the a* and b* values eachmeasured on the optical film structure at a near-normal incidentillumination angle.

Embodiment 27. The article of any one of Embodiments 23-26, wherein theoptical film structure comprises a residual stress in the range fromabout −1000 MPa (compressive) to about +50 MPa (tensile).

Embodiment 28. The article of any one of Embodiments 23-27, wherein theinorganic oxide substrate comprises a glass selected from the groupconsisting of soda lime glass, alkali aluminosilicate glass,alkali-containing borosilicate glass and alkali aluminoborosilicateglass.

Embodiment 29. The article of Embodiment 28, wherein the glass ischemically strengthened and comprises a compressive stress (CS) layerwith a peak CS of 250 MPa or more, the CS layer extending within thechemically strengthened glass from the first major surface to a depth ofcompression (DOC) of about 10 microns or more.

Embodiment 30. The article of any one of Embodiments 23-29, furthercomprising any one or more of an easy-to-clean coating, a diamond-likecoating, and a scratch resistant coating, disposed on the optical filmstructure.

Embodiment 31. The article of any one of Embodiments 23-30, wherein theplurality of alternating high index and low index layers is at leastfour (4) layers, wherein each layer comprises one or more of asilicon-containing oxide and a silicon-containing nitride, and furtherwherein the silicon-containing oxide is silicon oxide and thesilicon-containing nitride is silicon nitride.

Embodiment 32. The article of any one of Embodiments 23-31, wherein thehigh index layer that is adjacent to the capping low index layercomprises a physical thickness of about 70 nm or more, and the cappinglow index layer comprises a physical thickness of about 80 nm or more.

Embodiment 33. The article of any one of Embodiments 23-32, wherein thearticle exhibits a specular component excluded (SCE) value of 0.2% orless, as measured according to an Alumina SCE Test.

Embodiment 34. An article comprising:

an inorganic oxide substrate comprising opposing major surfaces; and

an optical film structure disposed on a first major surface of theinorganic oxide substrate, the optical film structure comprising aplurality of alternating high index and low index layers with a firstlow index layer on the first major surface of the substrate and acapping low index layer,

wherein a refractive index of the low index layers is within a range ofa refractive index of the substrate such that the refractive index ofthe low index layers is less than about 1.8, and wherein the high indexlayer comprises a refractive index that is greater than 1.8,

wherein the article exhibits a hardness of 8 GPa or greater measured atan indentation depth of about 100 nm or a maximum hardness of 9 GPa orgreater measured over an indentation depth range from about 100 nm toabout 500 nm, the hardness and the maximum hardness measured by aBerkovich Indenter Hardness Test,

wherein the article exhibits a single-surface photopic averagereflectance that is less than 1%,

wherein the optical film structure further comprises 35% or more of thehigh index layer by volume,

wherein the high index layer exhibits a maximum hardness of 18 GPa orgreater as measured by a Berkovich Indenter Hardness Test over anindentation depth from about 100 nm to about 500 nm on a hardness teststack comprising the high index layer with a physical thickness of about2 microns disposed on the inorganic substrate, and

further wherein the article exhibits an a* value, in reflectance, fromabout −10 to +5 and a b* value, in reflectance, from −10 to +2, the a*and b* values each measured on the optical film structure at anear-normal incident illumination angle.

Embodiment 35. The article of Embodiment 34, wherein the high indexlayer exhibits a maximum hardness of 21 GPa or greater as measured by aBerkovich Indenter Hardness Test over an indentation depth from about100 nm to about 500 nm on a hardness test stack comprising the highindex layer with a physical thickness of about 2 microns disposed on theinorganic substrate.

Embodiment 36. The article of Embodiment 34 or Embodiment 35, whereinthe article exhibits a specular component excluded (SCE) of 0.2% orless, as measured according to an Alumina SCE Test.

Embodiment 37. The article of any one of Embodiments 1-11, wherein thearticle exhibits a single-side average transmittance of greater than orequal to 87% in the infrared spectrum from 900 nm to 1000 nm.

Embodiment 38. The article of any one of Embodiments 12-22, wherein thearticle exhibits a single-side average transmittance of greater than orequal to 87% in the infrared spectrum from 900 nm to 1000 nm.

Embodiment 39. The article of any one of Embodiments 23-33, wherein thearticle exhibits a single-side average transmittance of greater than orequal to 87% in the infrared spectrum from 900 nm to 1000 nm.

Embodiment 40. The article of any one of Embodiments 34-36, wherein thearticle exhibits a single-side average transmittance of greater than orequal to 87% in the infrared spectrum from 900 nm to 1000 nm.

Embodiment 41. A consumer electronic product, comprising:

a housing comprising a front surface, a back surface and side surfaces;

electrical components at least partially within the housing, theelectrical components comprising a controller, a memory, and a display,the display at or adjacent the front surface of the housing; and

a cover substrate disposed over the display,

wherein at least one of a portion of the housing or the cover substratecomprises the article of any one of Embodiments 1-40.

What is claimed is:
 1. An article comprising: an inorganic oxidesubstrate comprising opposing major surfaces; and an optical filmstructure disposed on a first major surface of the inorganic oxidesubstrate, the optical film structure comprising a physical thicknessfrom about 50 nm to less than 500 nm, a plurality of alternating highindex and low index layers with a first low index layer on the firstmajor surface, and a capping low index layer, wherein each low indexlayer comprises a silicon-containing oxide and each high index layercomprises a silicon-containing nitride or a silicon-containingoxynitride, and further wherein the article exhibits a hardness of 8 GPaor greater measured at an indentation depth of about 100 nm or a maximumhardness of 9 GPa or greater measured over an indentation depth rangefrom about 100 nm to about 300 nm, the hardness and the maximum hardnessmeasured by a Berkovich Indenter Hardness Test.
 2. The article of claim1, wherein the first low index layer is in direct contact with the firstmajor surface of the substrate.
 3. The article of claim 1, wherein theinorganic oxide substrate comprises a glass ceramic or a glass selectedfrom the group consisting of soda lime glass, alkali aluminosilicateglass, alkali-containing borosilicate glass, and alkalialuminoborosilicate glass.
 4. The article of claim 1, further comprisingany one or more of an easy-to-clean coating, a diamond-like coating, anda scratch resistant coating, disposed on the optical film structure. 5.The article of claim 1, wherein the optical film structure comprises aphysical thickness from about 50 nm to about 350 nm.
 6. The article ofclaim 1, wherein the plurality of alternating high index and low indexlayers is four (4) layers or less, wherein a combined physical thicknessof the high index layers is 30% or greater than the physical thicknessof the optical film structure, and further wherein the capping layer hasa physical thickness of 80 nm or more.
 7. The article of claim 1,wherein the physical thickness of the optical film structure is fromabout 50 nm to less than 350 nm, wherein a combined physical thicknessof the high index layers is 30% or greater than the physical thicknessof the optical film structure, and further wherein the capping layer hasa physical thickness of 80 nm or more.
 8. The article of claim 1,wherein the physical thickness of the optical film structure is fromabout 50 nm to less than 325 nm, wherein a combined physical thicknessof the high index layers is 35% or greater than the physical thicknessof the optical film structure, and further wherein the capping layer hasa physical thickness of 100 nm or less.
 9. The article of claim 1,wherein the plurality of alternating high index and low index layers issix (6) layers or less, wherein a combined physical thickness of thehigh index layers is from about 30% to 45% of the physical thickness ofthe optical film structure, and further wherein the capping layer has aphysical thickness of 100 nm or less.
 10. The article of claim 1,wherein the article exhibits a single-side photopic average lightreflectance that is less than 2%.
 11. The article of claim 1, whereinthe article exhibits a single-side average light reflectance that isless than 2% over an optical wavelength regime in a range from about 400nm to about 800 nm.
 12. A consumer electronic product, comprising: ahousing comprising a front surface, a back surface and side surfaces;electrical components at least partially within the housing, theelectrical components comprising a controller, a memory, and a display,the display at or adjacent to the front surface of the housing; and acover substrate disposed over the display, wherein at least one of aportion of the housing or the cover substrate comprises the article ofclaim
 1. 13. An article comprising: an inorganic oxide substratecomprising opposing major surfaces; and an optical film structuredisposed on a first major surface of the inorganic oxide substrate, theoptical film structure comprising a physical thickness from about 50 nmto less than 500 nm, a plurality of alternating high index and low indexlayers with a first low index layer on the first major surface of thesubstrate, and a capping low index layer, wherein each layer comprisesone or more of a silicon-containing oxide, a silicon-containing nitride,and a silicon-containing oxynitride, wherein a refractive index of thelow index layers is in a range of a refractive index of the inorganicoxide substrate such that the refractive index of the low index layersis less than about 1.8, wherein the high index layer comprises arefractive index that is greater than 1.8, and further wherein the totalvolume of each of the high index layers comprises about 30% to less than50% of the volume of the optical film structure.
 14. The article ofclaim 13, wherein the first low index layer is in direct contact withthe first major surface of the substrate.
 15. The article of claim 13,wherein the optical film structure comprises a physical thickness fromabout 50 nm to about 350 nm.
 16. The article of claim 13, wherein theplurality of alternating high index and low index layers is less thansix (6) layers.
 17. The article of claim 13, wherein the total volume ofeach of the high index layers comprises about 30% to about 45% of thevolume of the optical film structure.
 18. A consumer electronic product,comprising: a housing comprising a front surface, a back surface andside surfaces; electrical components at least partially within thehousing, the electrical components comprising a controller, a memory,and a display, the display at or adjacent to the front surface of thehousing; and a cover substrate disposed over the display, wherein atleast one of a portion of the housing or the cover substrate comprisesthe article of claim
 13. 19. A scratch resistant article comprising: aninorganic oxide substrate comprising opposing major surfaces; and anoptical film structure disposed on a first major surface of theinorganic oxide substrate, the optical film structure comprising aphysical thickness from 200 nm to less than 450 nm and one or more of asilicon-containing oxide, a silicon-containing nitride, and asilicon-containing oxynitride, wherein the optical film structurecomprises a capping layer and a plurality of alternating high index andlow index layers with a first low index layer on the first major surfaceof the substrate, the plurality of alternating high index and low indexlayers is four (4) layers or less, and further wherein each low indexlayer and capping layer is silicon dioxide and each high index layer issilicon-containing nitride or a silicon-containing oxynitride, whereinthe capping layer has a physical thickness of 80 nm or more, wherein acombined physical thickness of the high index layers is 30% or greaterthan the physical thickness of the optical film structure, and furtherwherein the article exhibits a single-side photopic average reflectancethat is less than 2.0%.
 20. The scratch resistant article of claim 19,wherein each of the low index layers has an optical thickness from 2 nmto 200 nm, wherein each of the high index layers has an opticalthickness from 2 nm to 500 nm.
 21. The scratch resistant article ofclaim 19, wherein the physical thickness of the optical film structureis from 200 nm to less than 350 nm.
 22. The scratch resistant article ofclaim 19, wherein the inorganic oxide substrate is a ceramic substrate.23. A scratch resistant article comprising: an inorganic oxide substratecomprising opposing major surfaces; and an optical film structuredisposed on a first major surface of the inorganic oxide substrate, theoptical film structure comprising a physical thickness from 200 nm toless than 450 nm and one or more of a silicon-containing oxide, asilicon-containing nitride, and a silicon-containing oxynitride, whereinthe optical film structure comprises a capping layer and a plurality ofalternating high index and low index layers with a first low index layeron the first major surface of the substrate, the plurality ofalternating high index and low index layers is six (6) layers or less,and further wherein each low index layer and capping layer is silicondioxide and each high index layer is silicon-containing nitride or asilicon-containing oxynitride, wherein the capping layer has a physicalthickness of 80 nm or more, wherein a combined physical thickness of thehigh index layers is from about 30% to 45% of the physical thickness ofthe optical film structure, and further wherein the article exhibits asingle-side photopic average reflectance that is less than 2.0%.
 24. Thescratch resistant article of claim 23, wherein the inorganic oxidesubstrate is a ceramic substrate.